There are many tube amp circuit designs. I don't know about OTL amps though I hear they sound terrific, but the tube amps I've had all require a load to avoid trouble.

I think sound quality should be the overriding design goal of a tube amp. I've had tube amps for years and have never come close to driving one without speakers on line. I guess once you know not to it's simple. I'd agree that solid state amps should be idiot proof given the mass market target.

Enjoy the Music. Trust your ears. Laugh at Folks Who Claim to Know it All.