For a short period of time, sure.. but the ecosystem evolves quickly, and often in inexplicable ways.
> In the majority of cases WebAssembly is just give to give the lazy an excuse to use a language they already know rather than learn something new.
Most people program in return for money, not for self-satisfaction at learning yet another single-purpose language.
> But is a dozen incompatible, competing rendering frameworks (that each site downloads separately) going to be good for the web?
How is this significantly different from where we are now?
is a weird way of describing learning the language native to the web platform. I don't see a lot of people screaming about having to learn Objective C or Swift to make iOS apps.
> How is this significantly different from where we are now?
Err, because the DOM is a universal standard that comes built-in to every browser? <div style='background:red'/> looks the same everywhere, with no extra code required. If you're building a new renderer from scratch you're going to have a lot more code users need to download.
Now that we think about it, even with the DOM/CSS UI framework built into the browser, people still make use of libraries like jquery so library caching is something the browser needs to do anyway, WASM or not.
The JS ecosystem is a complicated mess, it's undeniable. But once you take the time to learn it, it's fine. In the majority of cases WebAssembly is just give to give the lazy an excuse to use a language they already know rather than learn something new.
And as for abandoning the DOM... yeah, it's not a great model. But is a dozen incompatible, competing rendering frameworks (that each site downloads separately) going to be good for the web?