You certainly can.
It’s just usually, you get so busy just trying to own & dominate one, that it rarely works out in practice.
Veeva is one of the more successful SaaS IPOs and start-ups of all times. It started off with a thesis of doing multiple vertical CRMs on top of Salesforce. It started with Pharma.
And it turned out Pharma was so large — it never left. That vertical “alone” got it to a $3.5 billion market cap, hundreds of millions in ARR, and far, far beyond.