How do products succeed without much differentiation?

Recently I've seen products in highly competitive markets like email marketing, Twitter automation, notion blogs, etc succeed without having much differentiation between each other

Like between MailChimp and convertkit I don't see much difference in features and values offered and even if there are some differences in features there isn't really much emphasis on that from them.

Then there are the intercom like tools with not much differentiation between them and still succeeding.

So my question is, even in crowded markets how do products succeed with so little differentiation?

Do they find users for whom that one small feature really is that big of a deal? Or is it when a famous founder starts something new or endorses something, that gets a lot of users?