Just because I trust a server to hold the cert for preview.example.com doesn’t mean I’d want it to be able to pose as prod.example.com, for example.
There are certainly other strategies and best practices that can mitigate the risk in this scenario, but not using wildcards is a good one to include.
That's not every organization.
I maintain many groups of /related/ servers (including dynamic ones which appear and disappear at whim). There, a wildcard makes a lot of sense. If I have https://[username].[domain]/, https://[git project].[domain]/, https://[client].[domain]/ or similar, that integrates nicely with a lot of security infrastructure in ways which http://[domain]/client/ don't.
E.g. A network can filter https based on domains, but can't look inside the envelope. A browser will highlight domains to users who want to know where they are. Etc.
There are also many good reasons why managing one credential per server (which can map to many domains) is better practice than managing a dizzying array of credentials.
So I agree about the general best practice, but there are exceptions. Mandating (as opposed to recommending / encouraging) non-universal best practices is usually bad practice.
Dave can test his stuff on a newly bought domain for testing or the internal domains.
Yours is not an argument against wildcard certificates! Yes, like, everything else ever, wildcard certificates can be misused.
But yeah generally speaking, it's best to avoid wildcards unless there's an actual benefit to using them, even when it's not a prod domain.
every branch
* several test data sets
* several feature flag / configuration sets
* ...
Having domain-constrained sub-CA certificates granted by the exact same mechanism we use for wildcard certs today would combine the advantages of both.
