The issue is that :
- if you recommend people to add a wildcard, you end up with the issue you’re describing
- if you don’t, everytime the user needs to add a new subdomain (for example to install an app that does need a dedicated (sub)domain), then you’ll also need to add the corresponding A record in the DNS and this is boring as hell
There are some ways to improve both situations but they have some other caveats or require developments