It's a scale, and if you put 5E at medium (especially in the middle of medium), then you create a ridiculous situation where almost all games are light or medium.
5E has more and more complex rules (even accounting for exception-based design) than easily 85% of games out there (especially 2024, which somehow managed to make 5E slightly rules-heavier, albeit also slightly more sense-making in some areas!). 3E and PF1 aren't that much heavier than 5E, they just have even more exception-based content. World of Darkness (in any version) is arguably lighter than, or on-par with 5E (arguably! Conventional forms of Exalted are maybe as heavy or heavier). Things like Daggerheart, which is not a simple game, are significantly lighter than 5E (I'd say that's towards the heavier end of medium crunch).
You could make a generalized argument that, compared to the 1990s, most games are lighter-crunch than they used to be, and that's a valid argument, but if we're looking at games today (even if we include ones published in the past and not really played anymore), because of the far higher number of RPGs out there today, 5E is absolutely at the lighter end of heavy crunch.
I mean, let's look at the top 20 on Drivethru today:
1) Daggerheart - Lighter than 5E
2) Legend in the Mist - Lighter than 5E
3) Cosmere - Lighter than 5E
4) Ashes Without Number - Lighter than 5E
5) A Legend of the Five Rings sourcebook - Don't know for sure, but going to guess current Lot5R is lighter than 5E (correct me if I'm wrong Five Rings fans!)
6) Warhammer: The Old World - Lighter than 5E (albeit maybe by less than the others)
7) Cosmere sourcebook - see above
8) Exalted 3E sourcebook - Exalted 3E is as heavy or heavier than 5E
9) Imperium Maledictum sourcebook - IM is lighter than 5E (it's a surprisingly light game, towards the low-middle of medium crunch)
10) Mythic Bastionland - Hugely lighter than 5E
11) A 3PP 5E sourcebook
12) The Outer Darkness solo TTRPG - Don't know, pretty sure it's hugely lighter given it's solo though
13) Coriolis sourcebook - Despite owning Coriolis I don't know it well, but it says Year Zero Engine and that's lighter than 5E
14) Daggerheart again - see above
15) Mutants and Masterminds 4E sourcebook - Not familiar with M&M 4E. Previous editions were lighter than 5E but not by a huge amount, so let's guess "about the same as 5E" (M&M 4E fans correct me)
16) Traveller sourcebook - I actually have so little idea re: current Traveller I'm not even going to guess - feel free to enlighten me.
17) CoC adventure - CoC is much lighter than 5E (even though it's surprisingly heavy for what it is, and into medium crunch)
18) Warhammer: The Old World - Lighter than 5E
19) Cosmere again, see above
20) Cyberpunk RED - Being generous you could maybe claim similar crunch to 5E?
So of these 20 games referenced by the top 20 in Drivethru, only one is plausible to argue as being heavier than 5E (Exalted 3E).
Two or three are about the same.
The vast majority are clearly lighter.
I think people sometimes let 5E off easy crunch-wise because of the exception-based design, and you can definitely cut a game a break for that a bit, but still, 5E has a ton of really specific and weird rules, like how it handles surprise, stealth, healing (hit dice!), loads of unnecessary extra things to track (six different saves!), lots of really inconsistent stuff (CON basically isn't a stat in the same way the other five are), the surprising complexities of Actions, Reactions and Bonus Actions and how spells interact with them (not in a intuitive or obvious way!), and what exactly an Attack is vs a Weapon Attack or the like (admittedly 2024 made that last one a little less twisted, but it's pretty twisted in 2014).
None of this makes 5E a "bad game" or "unplayable"!
It clearly isn't either of those things. But the slow piling up of specific and unintuitive rules, often with quite complex conditionality and the interesting decision to write the rules (including on the exception stuff) in an MtG-esque way mean it is, imho, very definitely a rules-heavy game by modern TTRPG standards, even if by 1989-1993 standards (which is I think what you're judging it on), it wouldn't have been.
