Working in the EU energy sector where we have to work with NIS2 compliance, I'd argue that your security team rightly pointed it out. I suspect that's what you mean though, and the rightly is just there because you agree with it but don't like it. We work with even more tight dependencies policies than just having alerts. We have a set of pre-approved and yearly vetted packages, like pandas or pyarrow for Python data work. Aside from that we have some isolated development environments where your pipeline can get access to something like SQLC for Go. Which is essentially where your dev dependency lives in it's own environment where it can produce the code it needs to and then submit it for approval into your regular dev environment.
Ironically we'd probably need to run Dependabot itself in a mirrored environment since it too has external dependencies we'd probably not want to vet.
I do think external dependencies are among our biggest security threats though. It's so hard to vet them, and compliance basically comes down to "We trust the apache software foundation enough, and pyarrow is vital to our business, so we accept the risks", and then you lock versions and aren't the first to update except for vulnerabilities. Shadow AI is obviously the number one security threat right now, especially in enterprise with people who are very tech savvy. This makes dependencies so much worse though, because now everyone can (if their systems aren't locked down tight) do so many crazy things. Both with the "non-sanctioned" AI but also with the code it can generate for them.