How do I make Teemo work?

I've been playing this guy for years now, and I have never been able to carry matches with him. It's always something out of my control that prevents me from ever going over a 50% win rate. If your teammates are doing poorly, there is next to nothing you can do as Teemo to help them because your teamfight is shit. You can win lane, successfully gank, successfully place vision shrooms in key locations (that your low-elo teammates will ignore because they're blind) and it doesn't mean a goddamn thing if your team isn't doing their job.

You can't carry with this guy. Not in this meta. Not in low-elo. I have tried and tried.

What is he supposed to be good for? Vision? Anti-splitpush? Objective control?

What's the point, if in low-elo none of your teammates ever seem to take advantage of his ultimate? They never stop splitpushers even if shrooms throw a kink in their advance. They never seem to see or care about the enemy jungler who just passed by 2 shrooms on the way to bot, and whom I pinged for repeatedly.

Sweepers confound the issue further, because now I must either build AD and become an underpowered ADC questioning why I went Teemo instead of Kindred or Graves, or I have to build AP and risk losing viability because 1-2 smart players on the enemy team decided to grab the red trinket and make any efforts at placing battle shrooms impossible. He has a terrible AA range for a squishy marksman, a useless W active that serves no purpose in an engagement and doesn't help escape in the least, a Q that's only ever useful for a little burst, or some very clutch scenarios where the ADC is stupid enough to 1v1 me without support.

I have no mobility in teamfights, no reliable CC (thanks to sweepers), a blind that will probably never get used for its intended purpose because doing so means I have to actually reach the ADC which is usually a death sentence or flat-out impossible without burning flash. I have some consistent single-target dps that never gets used to its fullest because of how quickly I can be killed due to lack of escapes/cc/durability (without itemization that sacrifices dps).

So how on earth do you ascend the ranked ladder, particularly in low-elo, using Teemo? What does he bring to the table that makes his success a potential win condition in the game, that isn't completely reliant on help from teammates to become a reality?