Not at all for me. I've had many more Snorlax/Lapras spawn the last few weeks before the Hallowe'en event than I did at first. Had 2 Snorlax and 1 Lapras throughout the first ~11 weeks, then had 2 Snorlax and 3 Lapras and 1 Dragonite in the last ~5 weeks before Hallowe'en. Also played a LOT more at first (like explicitly went out and walked around for 5-10km every evening, whereas now it's like 2-3km after work).
GamePress
Rare Spawn Theory
I can remember a time when it seemed like once a day, a new pokemon that I've never seen would spawn nearby. Specifically once I was in the middle of nowhere and I opened the app, and 30 seconds later a rapidash spawned on top of me. It couldn't have been a prior spawn point and wouldn't have made any sense except that I opened the app for something to spawn there.
I've since wondered if new users are key to the spawning frequency of rare pokemon. If each new user would generate one new random spawn each day, it would to me explain a lot. Anyone have similiar experiences seemingly getting one new pokemon a day nearby when you were a beginning player?