Whilst I'm sure it has had an big impact, I'm not convinced this is all down to Russian sanctions.
You're right, it's not
entirely due to the sanctions relating to Russian tourists but the fact they'll have have thousands of bookings, both block and individual, cancelled over the past few months is probably the straw that broke the camels back after a relatively poor season last year.
Many hotels close over the Winter but have cash coming in in the form of deposits and advance payments for accommodation. I suspect many rely on this small amount of money to get their places ready for the summer and those that don't probably get loans from the banks (on the basis that they can show sufficient advance bookings) to get started.
That section of coast further East from Fethiye relies heavily on Russians, Germans and Scandinavians - the Russians ain't coming, the Germans are cancelling in their droves (after Istanbul bombing) and who knows about the Scandi's.
Going off on a slight tangent, the cruise lines are bailing from Turkey as well - several have dropped Turkish ports from their itineraries and thats going to affect just as many smaller businesses as the absence of Russians in Antalya will affect hoteliers. Ironically, the smaller bars and restaurants in Antalya/Alanya probably wont see much difference, Russians are viewed as poor spenders and rarely eat outside their AI hotels.
JF