I am so disappointed this article didn't even touch on AoE2 - it has a pretty amazingly well tuned approach to this problem with extremely finely targeted (except back when camels were technically boats cough) bonus damage system. To compare it to SC2 is hilarious - SC2 has more hard counter systems than most games (both visibility and flight are common uncounterable attributes) and yet for all that countering tends just to be a question of how much and how wide the splash damage is when attacking tightly packed formations. High level SC2 eschews huge portions of the roster since they're essentially irrelevant - AOE2 definitely has strong preferences but most of those units get to see action pretty regularly... except the siege tower.

High end SC2 is really awesome to watch these days, most units get made and there are a lot of strategies available to either side. The balance team has done a great job making sure every unit has a role and is used.

The community staying very active has been the biggest factor here IMO. The predecessor to the current Definitive Edition, the rather disastrous (engine-wise, not content-wise) HD Edition, was created in part by co-opting community made mod content and hiring on some of the creators. This has continued for both the Definitive Edition and AOE 4.

Likewise, most of the biggest pros and casters started their careers 5-10+ years ago working on community tournaments and other grassroots events. Even though there's a lot more money now with investment from Microsoft, Red Bull and others, that grassroots core has stuck around and feels (at least to me) more fresh than the very corporate machinery around Blizzard RTSes. It's funny to think that the most anticipated LAN tournament is literally held in someone's apartment (https://www.ageofempires.com/news/nac3-tournament/)!