This is a topic I've been thinking about a lot. I strongly believe that these two genres are different. Collectathons have platforming, but I want to explain why I think they are different.
Platformers, in my eyes, are games like Sonic (2D and 3D), The Mario games (3D too, more on that later), Shantae, Rayman (all of them), Crash Trilogy, The DKC Trilogy, and most recently, A Hat in Time. Collectathons are games like Banjo, DK64, Conker's Bad Fur Day, and Psyhonauts. The former focus more on getting through stages. Sure, you find stuff, but it's more about the journey, then the end. Even though you enter and explore worlds non-linearly in SM64, you are still essentially getting to the end of a stage. Instead of a flag, you get a star. There are two collectibles in SM64. Coins, and Stars (and I guess technically keys, but there's only 3 so..).
This game begins to introduce elements that would become staples of the collectathon, but at its core, I still believe it is more about platforming through a "stage", then finding stuff. Rayman 2 is a straight up stage based platformer. It has cages, and Lums. Two collectibles. Cages are completely optional save for the obvious one at the end of each stage, and Lums can be mostly ignored, but you'll need a few to get through certain gates. Sonic? Get through stages FAST. Sonic has stuff you can find in all games, but it's still always (mostly) been about using your skills and abilities to navigate through stages.
Collectathons came about after SM64. They function like platformers, but feel the need to "give us more to do" so they are often comprised of sprawling levels with several collectibles, on top of a main MacGuffin. You don't focus on getting through stages as much as you do on finding things within a stage to do to get a reward. I..never got into Banjo (Though from an outsider's eye, it still looks better than DK64 by a small margin). DK64 was fun when I was a kid, but looking back, it is such a slog. I played the Wii U version recently, and yeah, it just wore me down. Unlike the DCK games, where I go through levels, I'm hunting down a bajillion things, traversing the same area again, and again. Back to Mario though, 3D Mario has always kept a balance. Sunshine is about as collectathon as the series gets, but I love that game. Galaxy 1, and 2, and the 3D Land/ World games appeal more to what I personally like about platformers.
I don't like the collectathon formula as much as regular platformers. I don't like how it replaced more traditional stage-based platformers when 3D became the norm. That's why I love Rayman 2 so much. It's a real, 3D platformer. It doesn't try to be anything else, and it's a great game because of it. It doesn't need a hub world. It didn't need a million things to find. The levels were fun, unique, and action packed. Collectathons ruined platforming, in some ways, but, I'll admit, there are still good collectathons. I still like the platforming segments in every game mentioned, I just wish there was more of it, cause that's thre best part for me. That's why I play these games. I don't want to find stuff. I want to play a game. Mario 64 is a great balance. Rayman 2 is a great platforming game. DK64, and from what I've seen, Banjo, just kinda take it to the extreme. You got 8-9 worlds in those games, so you'll be spending a lot of time there. SM64 had 15 main levels, with about 6-7 smaller areas. Rayman 2 has 19 unique stages, with about 15 different themes.
And, a Hat in Time hits this balance pretty damn nicely too. It's like.. up there, it's a good game. That's the reason I made this thread. If we want this genre as a whole to succeed in 2017+, we need to acknowledge the differences within that genre. It's okay to have different styles, but I feel like any 3D platformer is expected to be a collectahton, but they don't all need to be, and they surely shouldn't all be. This is important so that not everyone on the outside sees this genre as DK64s and Yooka-Laylees, in case they don't like that style.
Thoughts?