Microsoft 365 ships open. A new tenant will let anyone sign in from any device, anywhere in the world, with a password alone, and nothing complains or breaks. There is no error message for a tenant that has no conditional access policies. You just end up with a gap between what you assume is happening and what's actually enforced.
The gap usually shows up in the same few places. MFA is on for most people, but not the service account nobody remembers creating. Legacy authentication is still enabled because turning it off might break the scanner in accounting. Personal phones sync company mail with nothing in the way. Six people are Global Administrators because that's what "make them an admin" did at the time.
None of that is negligence. It's what happens when atenantgrows one request at a time over five years and nobody's job was to look at the whole thing.