The amount of bundlers I've seen in my time is borderline obscene. Nowadays it's even worse, as every javascript framework developer's actual secret fetish is to build their own bundler. Ideally in Rust because that's hip I guess.
Webpack, Snowpack, Parcel, Rollup, Esbuild, Vite, Turbopack... just stop. Enough.
I've managed to cut down build times from ~1min (sometimes up to 3, but I couldn't even tell you why) when using Webpack and Babel to less than 200ms using just Rsbuild.
So, I welcome the improvement! The fact multiple people/orgs felt the need for this clearly means they felt the pain of slow builds too.
I'm sure people tied up in the roll-up ecosystem think the same about Vite and rolldown!
All these do things subtly differently in ways they think is the correct way. Maybe one will come on top or maybe something else comes along and integrates lessons from both and that eventually wins and all meintence moves there eventually.
The JS ecosystem is complex (for better or worse), and bundling for it isn't a simple as people believe. So it makes sense there's multiple things trying to tackle the same problem!
I prefer to spend my time building against that instead of another bundler.