Is there a point to going tank in low elo ranked games
As far as I've found being a tank top laner is my favourite role. I love going Cho'gath or Sion and being nigh unkillable while guarding my carries.
However, every time in ranked I win my lane, push it out, try and roam or make tp plays for objectives but it never seems enough to make my team win.
You can only peel so much for idiots. As a tank I can't secure objectives single handedly nor do I deal significant damage. I just peel and cc enemy carry's while I pray mine aren't brain dead and will do their job for once!
I've lost my third promos in a row and almost every time I win one game lose another and the last one is close but some fool makes a mistake, like my ahri running away at half health leaving me and jinx to die cause I can't peel for her alone.
win lane lose game gg bronze hell forever.
What I'm asking is, Should I just abandon the concept of being a tank in ranked and pick more carry based champions and roles so I can stop depending on others or Riot matchmaking gods giving me good teammates? Should I just focus on split-pushing and doing it all myself?
I know its a team game but sadly other people aren't reliable whereas I know my limits/skills and can trust in them.
lol, they sure do delete squishies don't they.

No. Don't bother in low elo soloQ, sometimes you get teammates who respond to every initiation, sometimes you get teammates who just don't do anything productive. The possibility of you getting a team that actually works with you isn't worth you sacrificing your damage and waveclear.
are excellent for soloQ, since they can do so much more by themselves than the other tanks. You will miss out on the initiation your team needs for late game fights, but oh well.