When my last company transitioned to cloud, all of the on-prem folks had to additionally take on that responsibility. We then had to hire a bunch of new folks to ease the transition and manage the cloud pieces. And then there are new teams spun up for permissions and security. Your headcount requirements are not going to go down because of cloud.
As for those that like to call DIY systems "weirdware": homegrown systems are expensive to engineer, but cheap to run. We 10x'd our cost going to 3rd party visibility and feature flagging versus the thinly staffed [1] homegrown systems. And those 3rd party systems also required a ton of engineering to support, the migrations weren't clean, and they missed a lot of key features that we had to upstream to the third parties!
When SignalFx got bought out by Splunk, I've never seen an annual plan get re-wired so hastily. Top priority was moving to a new vendor, and that impacted every single team in the company.
The only real tangible benefit to cloud that I've seen is that a team can instantly provision hardware, database, etc. resources without much planning. That's it. And is that worth it? (I don't really think so.)
[1] Once built, half an engineering headcount per quarter to accommodate new features. Oncall rotation for one team that owned the systems. Our stuff was high resiliency and barely paged at all. No SEV1 or worse outages ever.