Wasm comes with a garbage collector though, no? So a garbage collected language that offloads all memory management to the runtime would actually be better than one that ignored the platform and does its own stuff.
The JVM alone has, what, 4 different modern GCs now? Garbage collectors aren't really universal, so they can pose different issues for different languages.
Apparently there were some design issues (raised and ignored) that made it unusable for many languages.