[__d]

It depends.

A CTO is responsible for ensuring that the company is able to deliver what’s needed, and if the current stack has issues, including ok-now-but-won’t-scale issues, then they should switch it out for one that positions the company for success.

OTOH, it could be motivated by a range of unjustifiable things: personal familiarity, resume building, blind trend following, asserting of authority, etc.

In most cases, the engineering staff can tell whether the motivation is good or not.