Quite insightful! Being a part of product teams, I've noticed "platform" teams struggle and the reasons have mostly been not doing what you've pointed out above. As in, instead of working with their customers (i.e., other product teams) to identify their problems and fix them, they would push down their generic platforms down the throat. It invariably didn't end well.

I tend to think that platform/framework teams within a large orgs should be run as a B2B SAAS, at least with that mindset.

Also, if a platform team isn't run well, it ends up being the first one on the chopping block during layoffs. Uber laid off an entire developer-platform team earlier this year. One casualty was the Screenflow team, a promising product that didn't gain wider adoption due to terrible marketing/evangelism.