I don't know why. Maybe someone reported me for something to harass me for my politics, because that's what keyboard crusaders do. Maybe it's a FB glitch. In any case, I've submitted my ID to prove to FB that I am who I am. With luck, I'll have the account back soon.
And then I may disable it, because FB is such a timesink. No decision yet; if I leave FB, I'd like to say goodbye there before I go.
ETA: And I have my account back, maybe 45 minutes after I sent in my ID. No explanation for what happened, so I won't waste time wondering about it.