Things have not really changed in that regard.

Anyone who books on any major airline as "Doctor" has that printed on the manifest and BP etc AFAIK.

You might be a PHD, with a degree in Aboriginal art.

Or a MD.

If the latter they are OFTEN approached by FA's to give advice on Mrs Smith in 56B who is a bad way.

If the Doctor assists in some material way the are given a form to mail to HQ, and always get something nice as a 'thank you', depending on level of assistance. Free ticket, upgrade, voucher etc.

And MOST often, a seat up from for rest of trip if they are not already seated there.