"Don't want to manage their own" has for so long been a valid excuse but cloud costs haven't been going down for so long - in many cases prices have increased - and hardware keeps getting more badass. In so many cases it's fear speaking.
A decent sized server will host a hugely capable instance that you may not have to think about for years. The scoffing down at DIY has made sense to some degree, but it just works brilliantly keeps getting to be a stronger & stronger case & most just assume reality can't actually work that well, that it'll be bad, and those folks won't always be right.
But in this case we are not even talking about own/rented HW vs cloud. It's self-hosted(even on cloud) vs SaaS softwares!
SaaS, especially in this space, can be *extremely* costly and its cost will scale up quickly as you send more traffic (either willingly or by mistake). Yes, Datadog, NewRelic etc will give you many pre-built and well-thought dashboards and some fancy AI-powered auto-detection thing but they will charge many $$$ for it. Consider that now cost management/analysis tools that were historically focused only on cloud, are now adding the same tooling for costly SaaS solutions!
I understand that many HN readers are skewed towards SaaS solutions, usually because they work at a SaaS shop, but depending on the size of the company, the overhead for managing it internally can totally be worth. There is overhead with SaaS as well...
A decent sized server will host a hugely capable instance that you may not have to think about for years. The scoffing down at DIY has made sense to some degree, but it just works brilliantly keeps getting to be a stronger & stronger case & most just assume reality can't actually work that well, that it'll be bad, and those folks won't always be right.