Managing infrastructure is like a muscle
And companies that fail to keep that muscle struggle to get it back. Few companies, large or small, that have gone primarily cloud, could have managed moving back on-prem in less than two years (let alone switching providers, which is hard enough - by design). I'm impressed by what they accomplished.
I suspect that for many infrastructure support groups, a key focus becomes managing the cloud configuration personnel, to help them configure their resources better and with less error. However, those whose primary skillsets are solely in cloud configuration (as opposed to also having more general purpose skills) tend to not understand the systems or underlying reasons why things might be structured to work in a particular way (I don't mean all, I'm just pointing out what many of us have run into over the years). And it is inherently extremely dangerous to let those individuals operate without guardrails, so in general a lot of effort goes to making sure some dumb mistake doesn't wipe out the op-ex budget for next quarter, so bureaucracy and tooling enable a non-virtuous cycle, growing a rising percentage of barely-computer-literate individuals among IT, which causes a rise in guardrails and so on. So for some established companies with a short term mindset who don't want to waste investment on the future, the cloud just makes it easier to kick the can down the road. For others, the cloud is necessary for scalability and they treat their reliance on it with the appropriate long-term cautious mindset, where their use of cloud enables growth and margin that can be invested in people who want to grow their skills and give them the ability to do so. And for others like 37signals, moving on-prem turns out to be a cost-effective way to do all that at their scale.