Imagine you've never heard of Gmail before. How does "I generally steer them towards the Gmail clients" sound if someone asks you about email?

The difference is in marketing. Gmail is a service with its own official app and so on. Matrix is a protcol, you can't market a protocol to regular people. Other than techies, nobody cares how their chat works as long it works so if you want to gain traction you market Element as the new hot messaging app and not Matrix the protocol.

Isn't it pretty well understood that Gmail is an email service though?

I don't think that's a good example since Gmail is an email provider which can be used with any email client. Element is a Matrix client that can connect to a matrix provider.

What do you propose to do instead? To actively prevent people from creating clients for the protocol?

The Element clients are the closest to what you could consider official clients, being made by the Element company, which does most of the Matrix design and development.

What's preventing you from picking one at random, then?

The Paradox of Choice.