It used to be normal for steam sales to be somewhat rare and surprising, but the tradeoff was that it was the norm for big and popular games to have staggering discounts.

In 2012, Terraria went on sale for 25 cents. Valve sold the entire Half Life family for like two dollars. AAA and big name games would go for 80% off or more, back when that actually got you a full game without microtransactions or significant DLC to buy.

People got excited about the sales because you might wake up to find the game you really wanted for $60 was now a few dollars.

Objectively "Incredible" deals are a lot less common, and old stuff doesn't have massive discounts anymore, sticking with "just" very good discounts.

I still see some pretty staggering deals now and again, but maybe not to the extent you remember (I don't really remember that, but I was also primarily a WoW player back then, and didn't pay as much attention).

How much of that is to blame on steam vs. the publishers, though? I would imagine the publishers have much more control over (if not total control?) over pricing. So, unless I'm wrong, it seems misguided to put that at steam's feet.