TOFU has proven to be quite resilient against MITM attacks. Do you think it's a stretch to say that SSH is secure?
In reality, TOFU is a form of key verification and it is highly effective against MITM attacks because there's no way for an adversary to reliably determine whether or not a user is seeing a fingerprint for the first time. If at any point the fingerprint changes, the users are warned.
Users can also easily check and compare fingerprints too. They are not mutually exclusive.
Sure, TOFU is better than nothing, and might even be very good, but there's still a way for an active adversary to MITM you.
In order for an active adversary to perform a successful MITM attack against a TOFU scheme they would need to successfully determine when someone is seeing a fingerprint for the first time (or get lucky) and then successfully maintain their MITM position across every single network the device uses, forever. If they fail at either of those, the user will be warned.
I keep bringing up SSH because it's an example of a fingerprint verification system based on TOFU that works incredibly well at preventing MITM attacks. No one is having key signing parties with their servers, and yet connections remain secure.