Yes, it is poor coding/design/execution on their part, there is no reason that biometry can't be used for secure logins. I don't have to enter MFA every time; as long as the session is still valid, you shouldn't have to do that.
That said - I have had the MFA (multi-factor authentication) in place on my arbiter account for several years, due to the fact that besides being a scheduling platform, is also a facilitator of payments to me. So having it enabled is a good thing, as it can help prevent someone from getting your account information, or worse, using it to make withdrawals.
MFA, often called 2FA, is primarily based validating two of three things: something you know (your password), something you physically have (such as an authenticator app that gives a code, or a USB token that does the same thing), or something you are (your biometrics including fingerprints, iris scans, etc.), which are for the most part considered immutable.
It is a complete PITA the way they have it set up, yes, and there are much better ways to do it, but given how awful the mobile app is anyways, I wouldn't hold out much hope for any improvements anytime soon.
