Yes, there are 689 words left with 4 distinct letters, 57 with 3, and 1 word left that just has 2 distinct letters in it.

That word is a common enough English word ... warning, this is a spoiler for a puzzle that should appear in about 5 years ... "mamma"

I solved one the other week with repeated letters, answer was elder.

Yes we had KNOLL as an answer recently.

I would guess they just got removed because they were obscure. I remember past words with repeated letters.

'elder' is there