Alternative infrastructure costs money, and it's hard to get approval from leadership in many cases. I think many know what the ideal solution looks like, but anything linked to budgets is often out of the engineer's hands.

In some cases it is also a valid business decision. If you have 2 hour down time every 5 years, it may not have a significant revenue impact. Most customers think it's too much bother to switch to a competitor anyway, and even if it were simple the competition might not be better. Nobody gets fired for buying IBM

The decision was probably made by someone else who moved on to a different company, so they can blame that person. It's only when down time significantly impacts your future ARR (and bonus) that leadership cares (assuming that someone can even prove that they actually lose customers).