Hahah. That's a funny thought. I don't think it does lead inevitably to toxicity, though. I don't think the incentives it imposes are really that favourable to that sort of usage. There's a hedonic attractor for venomous behaviour rather than a strategic attractor.
Right now the char limit isn't really that hostile to dialogue. There's a "threading" UI (hints that it's okay to post many tweets at once) so it's now less like "don't put any effort into your posts" and more like "if you're gonna post a lot try to divide it up into small, digestible pieces"
If you want to explore the community more, I recommend reading the Library, checking recent Curated posts, seeing if there are any meetups in your area, and checking out the Getting Started section of the LessWrong FAQ.
The Open Thread sequence is here.