If it's so bloated then just start cutting

Whatever expertise you need to prune a working system is less than the expertise you'll need to create a whole new one and then also prune it as it grows old

Absolutely not.

Software is bloated in part because it's built in layers. People wrap things over, and over, and over. Stripping down layers is neigh-impossible later. Starting from scratch is easy.

Starting from scratch fails in practice because you don't get feature parity in time short enough for VC (or grant) funding cycles.

If we build a tech tree around 200MHz 32MB machines, except for things like ML and video, we'd have a tech tree which did everything existing machines do, only 10x more quickly in 0.1% of the memory. Machines back then were fine for word processing, spreadsheets, all the web apps I use on a daily basis (not as web apps), etc.

Need would drive people to rebuild those, but with a few less layers.