Now, i don't know the game that you're talking about and if i was in it / watching / whatever.
And assuming that it is Karl who reamed you about Baron 
First of all, you do have a habit of splitpushing often as a support. Sometimes that's fine, there's gold dying to tower... things are warded... no real objectives... neither team is grouped... etc. Some supports are just flat-out better at splitpushing than other. Fiddle kills stuff a lot faster than Nami, for example.
More probably, people saw you splitting bot slowly killing creep waves and internally went *sigh*. Even though the 4v5 midlane wasn't successful for the enemy team, they were frustrated to see you farming creeps botlane as a support at 30 minutes.
Even though you died for a tower + got 3-manned (an overall increase in team gold and relieves enemy pressure), sometimes your team was really far ahead and if you had just 5v5'd you could have gotten an Ace and an inhibitor.
Plus, trading towers for deaths isn't always a good idea once bigger objectives start coming into play. Trading a life for a tower at the 40 minutes can certainly lose games... Trading teleport, ult, flash and a death for a tower with only 50 hp remaining isn't a good trade either, regardless of the stage of the game.
Anyway my understanding of that particular situation (from whoever got the most angry) was:
1- pacov is splitpushing as a support again. argggg
2- oh well he got a tower. died for it. let's try to do something.
3- we misplay, damn it.
4- IF ONLY PACOV WASNT SPLITPUSHING. #3 could have been prevented by just 5v5'ing. RAGE.
Of course, #3 could also have been prevented by just ... not screwing up. Which is an important thing to consider. But people may not have been so frustrated during #1 and #4 if there wasn't a habit of you splitpushing as a support? The feelings of frustration may not have just came from that single game. Just like your feelings of frustrating don't come from a single game.
On the other hand, your post appears to summarize to be: "my team screwed up and then gave them baron, not me. And then they blamed me a lot. But i had a net gain since a tower is better than a death. But they just threw shit away. THEY gave them baron. Not me.".
A more accurate (and must less emotionally poignant) statement is "both my actions and my team's actions resulted in the enemy team getting baron".
Even though you "traded" a tower for a kill + baron versus your team trading nothing for 3 kills + baron ... it's still a negative trade.
Anyway, just a thing to consider when splitpushing... 1v0 is really easy. When a splitpusher kills a tower, it's really not "oh look guys i got a tower. look how good i am for the team". The other 4 people have to pressure and be pressured while you do that. That's the hard part. 1v0 is easy.
It's the same thing as soloing baron. If you're soloing baron at 18 minutes as Trynd/Nunu/Yi/whatever... the rest of your team can't just walk down together bot lane you know?
And so (frequently) you get the easy job, even though it might work out great and get us an inhibitor/dragon/baron/whatever. i mean splitpushing isn't ALWAYS the wrong thing to do. But when you get to just right click things and then say "well iiiiii got us a dragon. wtf are you guys doing?" tends to ... get people excited, to say the least.
Generally, our group doesn't really get annoyed by people:
1- playing new champions
2- feeding (as long as you aren't whining about jungle ganks constantly)
3- not having a lot of wards
4- missing smites
Our group does tend to get frustrated by:
1- bad initiations
2- extremely bad positioning or teamfight focus
3- poorly done splitpushing (eg, when everyone else is a base and you die for free. if baron is up. etc)
4- off-meta stuff (eg, double bruiser bot. certain champion choices like heal Garen against Nasus).
Pretty much... no one cares that much if you completely misplay the first 20 minutes of the game. If we have to deal with a 12/0 Tristana who wins the game at 23 minutes... at least it's over quick.
What does flare people up is when something terrible happens at the 40 minute mark. Part of that is because a lot of our group (myself, thunder, Cow, Karl) tend to gravitate towards teamfight focused champions and playstyle.
In closing... appealing to "normal games don't really matter why do you get so frustrated if i get to do ____ and throw" doesn't really work for our group since our group... mostly only plays Normals. It'd be different if it were more of an 80/20 split and when we played normals we were all drinking and doing stupid shit.
i do also think some of your frustration stems from being pidgeon-holed into support a lot recently. And when you get to play not-support, we get pissed off at Jungle Tryndamere (because it's a 4v5 for 15 minutes even if you get the early 800 gold dragon... and even if you carry at 40 minutes and win everytime. it's still frustrating). So you feel like either:
1- you play a role you have played way too much of recently and you don't want to do it anymore
2- when you do get a role you want to play everyone is angry at you before the game even starts.
Since it hasn't really been a problem with people getting invited and "stealing" mid when i'm in the group... i can definitely fill a bit more often. My original stance of "mid or dodge" was mostly because a few months ago i very rarely got mid and i was the fill-bitch and i got sick of it. i can certainly try to support more often if you think that is going to make the game a bit more enjoyable for you.