That's not quite unique, is it?

It may a per-tenant setting but I checked that and a new meeting created in Outlook doesn't contain a Teams link - you have to either select "New Teams Meeting" or select "New Meeting" and then explicitly make it a Teams meeting.

New meetings created in Teams do include a Teams link - but isn't that what you would expect?

In my work Outlook, it's similar to what GP says. There is only "New Meeting" (not "New Teams Meeting") and the message starts out with a Teams link, and then I actively have to opt out of that with an extra button press in the meeting composer.

You can disable that: Outlook Options → Calendar → Calendar options → Add online meeting to all meetings

I don’t like Teams, but I use it.

I like the auto Teams link because it saves me a click when setting up every meeting (and pretty much 99% of my meetings are Teams meetings).

I think this is a case where it makes sense to default on because most people will leave it defaulted on.