I'm not sure what game you played, but solo healer ques were consistent for all of ShB and SB for me. I've never had to wait more than 5 mins to get into ANYTHING as a healer that I can recall, and generally the window pops for me as soon as I hit the que button. It's done this consistently for...basically 8 years.
This I disagree with. Many people even back then didn't like healers, which is why there was a chronic healer SHORTAGE until ShB. That wasn't healthy for the game.
So which is it?

I haven’t seen a 5 minute queue for leveling, expert etc roulette as a solo healer once since the release of EW. Queues were typically rapid in EW but not as consistently instant as they are for me now. Go back to ARR, HW and even SB, they weren’t consistently and guaranteeably instant like they are now. They weren’t long sure. But again. They weren’t instant either.