I wouldn't go that far. A lot of games have drudgery built in which isn't exciting past the first few times you've played it and rare bouts of willingness to do it again.

I would position part of what made Diablo 2 (not remake) last so long was bots on the ladder and the shops that provided the bots; no one "new" was playing the game at that time and everyone had "fair cheats" for rushing through the first two game modes [0] [1], and everyone had been using the "fair cheats" for years since they had been discovered. But the fair cheats needed other players to pull off, and this wasn't always reliable.

When the D2 shop farmers started botting, they realized it would be great advertisements to do specific types of common runs for leveling with the bots; the bots would grab any item worth value, but typically they just would repeatedly run common leveling/item farming areas on a predictable and guided schedule, dropping quick announcements about the shop in chat periodically (maybe several times per run which is usually around 5-15 minutes, and it was just a quick stylized message in the game chat.) There were enough bots that it wasn't flooding the available games to join, but you could almost always find a bot game to join and just follow until you were leveled.

Most players did this to get through Normal mode and often nightmare, as everyone just wanted to get a character ready for late Nightmare/Hell which is when the game is "fun" (better drops, more difficult monsters to fight, it was the point at which the game gets interesting in general for most players)

Without the bots and players "cheating" through the first 2 game modes, I'm not as confident people would have keep playing as long as they did. It wasn't "unfair" in my opinion as everyone had always wanted this, and it had automated what everyone was already doing; I'm not sure I see the difference between using AHK like the GP did and having a setup like what D2 had

0 - For the unfamiliar, Diablo 2 had three modes: Normal, Nightmare, and Hell; same game each time, but item drops are better and monster levels are changed to be more difficult, with monsters getting better attributes that made them more difficult. I am going to make a generalized statement that for most players, the game really begins at Nightmare if it's not one of your first few times playing the game

1 - By "fair cheats" I mean the game was exploited to ensure fast leveling without a lot of effort and also ways of bypassing the "boring" parts of the game that the game allowed, but likely not intentionally. Blizzard definitely couldn't solve this in game without substantial reworks, which they probably didn't want to do

I dont know about which years you talk about but at least in the early 2000s it was probably most common to let yourself be lead through Normal/Nightmare by others (e.g. clan members), which was a very nice part of companionship that helped foster engagement (and thus play count). But maybe you and me were just in different bubbles...

Not sure you'll see this, but I played from release until they released D2:R (I want to play D2:R, just no time :) )

Early on that's how it was, but later on they figured out glitch rushes (grushes) to help you fly through a1-a3 and you'd usually just trade your forge on NM/Hell for it.

After awhile though, this got really scammy from my experience (too many players who needed to be rushed would just flake)

Around 2018 or so when I played again, there were a LOT of shop bots running around doing the runs, and even better you had ENCHANT games where some suped up sorc would cast a ridiculously leveled ENCHANT on you (and your merc!) and even get you waypoints. I think I even remember the bots could do the grush, but I'm not confident I remember right on this element.

Basically, yes, old team-ups were great, when the player base was significant enough that you could do this :) In the last years of D2/LOD original, it was a little less possible to go that route.

Other players can write automation too.