Then why did those company fight, and not just leave...?

Worth pointing out also that the US is the odd one out, here. Europe also enforces consumer rights.

A small, more ethical company filling the void Bambu Lab left can grow much faster and eat into Bambu's market share in a relatively short time.

Yes, it's not as simple as that, but it's not that impossible either.

The only place you can change contracts at will on the company side is the US, and even there it probably depends on the state.

This kind of firmware update to remotely disable feature is also illegal in the EU

Australian customer protection laws were the initial reason why Valve introduced refunds into Steam.