The only reason Microsoft is using Delta is to emphasize to CTOs and investors that fabric is as good as databricks, even when that is obviously false to anyone who has smelled the evaporative scent of vaporware before.
Regardless of the relative merits now, I think everyone agrees that a few years ago Slack was clearly superior. Microsoft could have certainly bought Slack instead of pumping probably billions into development, marketing, discounts to destroy them.
I think Microsoft could and would consider buying Databricks—$80–100B is a lot, but not record-shattering.
If I were them, though, I’d spend a few billion competing as an experiment, first.
The Trump folks have given mixed messages on the Biden-era FTC; I'd put the odds that with the right tap dancing (sigh) Microsoft could make a blockbuster like this in the B2B space work.