In the safety perspective, dormant accounts might be prone for exposed passwords (reused passwords, exposed via other services etc.) and easily an attacker can hijack your account. I had similar experience where a dormant apple account was hijacked and unable to recover. Apple also follows similar philosophies to sign in from a real device for recovery. Have you tried recovery options?
I always had given Firefox another choice, but throws me out of websites, unoptimized websites and font issues etc. stopping me from using it. I really wish Firefox tighten up their game.