And even if it didn’t, it increases the attack surface. Random apps can ask for root, and the average user won’t know what it means.
And even if you know the risks, now it’s much more of a hassle keeping your device up-to-date.
So yes, rooting is theoretically a solution, but it’s not practical in the least.
It's nice if this is a hobby (and I have rooted my phones in the past), but for the average user (even the average technical user) who just wants to get on with their day without becoming an expert in rooting, it's a complete no-go.
Importantly, it's a very poor substitute for regulations mandating that manufacturers offer us these options without having to go through back doors. I believe that any energy spent on technical workarounds to manufacturer locks is better spent on political activism to enable true device ownership through regulation.
Most people are not capable (or willing) to own their device to its full extent and take responsibility for it.
For most people "owning their devices" means being allowed to meaningfully change OS (or even just modify it) without losing major functionalities.