Hi! Thanks for reading! I totally understand what you're saying. My thing with just having Medium is what happens if Medium decides it's done next week? You have no power in your hands by keeping all your eggs in one basket like that. Or even a few baskets.
Diversifying your income streams as a writer is crucial to survival. I actually think newsletters are even more important than your own niche website. It gives you direct 1-on-1 access to your readers and offers several ways to monetize.
Just my thoughts though, I understnad your point. Never spread yourself too thin and again thanks for reading!!