This article is biased towards Blizzard-style RTS. Not a single C&C game mentioned. Not even RA2 and C&C:Generals, which had very healthy multiplayer scenes. Blizzard RTS games are extremely conservative by design, how are things supposed to get better if you're so conservative?
I think a fundamental problem is control method. In Blizzard RTS, you just must click fast. Lack of automation makes it worse. The interface pioneered by the first C&C game is suitable for commanding small squads. You draw a rectangle to select units and point them at a SINGLE target. There is no way to order snipers to only target infantry and bazookas to handle tanks. No way to tell infantry to keep distance so tanks don't run them over. You only have the primitive X key, which makes selected units move 1 square in a random direction. Limited ways to select multiple units. In most RTS games you can only select pre-configured squads or units of the same type. No way to quickly select only wounded units or only units close to enemy. Basically you can do everything you want but you have to click fast enough. That's like an elaborate version of "Applause for Xi Jinping", the game where you need to click as many times as you can over 9 seconds. Total Annihilation and Supreme Commander had some interface innovations, but it hasn't caught on. In general, I think RTS games should use many, many more keyboard commands and I don't mean just build unit and spell hotkeys. There is an over-reliance on mouse. Mouse scales very poorly with conflict size.
RTS games still haven't managed to implement a useful formation system. In Blizzard RTS, "melee units in front, shooters behind" is called a fine formation. Developers don't give players a formation system to deal with splash damage, they artificially limit impact area. There are very few flanking maneuvers.
Another sign this essay is biased for Blizzard games is no mention of scouting and information gathering. I suppose because it can't be further improved? In Blizzard RTS games, scouting is very rudimentary and you typically send a unit once in a while to enemy base to see what structures he has available. Then you call it a day. Information gathering is an extremely important part of warfare and it's stagnant in Blizzard RTS games. Sometimes you have a spell like Farsight or Satellite scan, which only reveals a small area for a very short time. There are no tools to survey the area between bases to give you an idea where enemies might be. Without proper scouting as a layer of contest, the game can become a match of rock, paper, scissors.
Incentives to spread your force. In this area, SC2 is actually a regression. A force is typically called a "ball", and you run one ball into another ball. There are no good ways to deal a lot of damage with a smaller force, so most players stick to a huge ball. There are no incentives to attack in 2 areas at once. By dividing your force you usually put yourself at a disadvantage.
Incentives to keep some money or units in reserve. There are none. It is usually considered bad play to have any money sitting in the bank - you haven't optimized your build order. You're doing fine if all your factories are producing at full capacity.
Starcraft players like to bring up Chess because they have an inferiority complex, but a better comparison might be playing guitar. To play both you need to practice, practice, practice until you can perform very well. You need to know what to do in advance. If enemy does something strange, you better know the counter already. It's not a game for thinking much.
In short, I think the essay author should play more non-Blizzard games to see how things can be done differently. Settlers, Northgard, Z, Planetary Annihilation, Total War series, Homeworld...