Walking down the aisles of any store selling computers, I can attest to this. If a company can't sell a Windows computer, they will simply sell a Chromebook instead.
verily
Two thoughts based on what you wrote:
There's a bit of an issue with that. Re-Centralization. If the grand majority of users are in the "Main" or "Primary" instance, it's just moving one mass from one to another, without spread...
I think it's plenty fine to recommend a specific instance to people. It doesn't need to be the main one either, it can even be yours:

Does the Fediverse have an equivalent to
matrix.to?
Not really. Probably because Matrix can "get away with" recommending some default software (including web apps) to view a community from any server, regardless of where it is, mostly because there's very few instances of that software to recommend. Matrix.to is a first-class service provided by the same people who run the flagship Element client and develop the server too, after all. And it's still limited: matrix.to will not point you towards a niche instance of Element, for example.
But things get worse when it comes to Mastodon and Lemmy because usually instances tend to act as both data servers and clients. If somebody sends their profile link to a friend, it goes to their server. People have implemented sharing techniques, but these are janky at best, and require extra configuration and pre-knowledge on the part of the recipient.
And I still don't know how to open a post from a different Lemmy instance on my current one without manually looking for the community and then the post.
I disagree! /s