Matrix supports both; when you're trying to get Matrix deployed on someone's domain it's a crapshoot on whether they have permission to write to .well-known on

Matrix supports both; when you're trying to get Matrix deployed on someone's domain it's a crapshoot on whether they have permission to write to .well-known on the webroot (and if they do, the chances of it getting vaped by a CMS update are high)... or whether they have permission to set DNS records.