Stale meta may have affected it somewhat but it's not the main contributor to SC2's lack of traction. I already posted this before but even Broodwar failed to see large growth outside of the Korean explosion. There were a handful of non-korean pros but the pro scene outside of Korea never scaled to the same level. EU & NA Esports are largely uninterested in the RTS viewing experience.

The only major fault i give to Blizzard is fooling themselves into thinking they'd be able to bring the Starcraft scene to scale in the west to the same level as Korea. They even tried region-locking to keep the Western scene from being devoured by Korean players.

But it was basically a fruitless effort, there's just not enough interest for RTS esports outside of Korea. They were better off removing any region locking for tournament circuits and letting the Koreans take over. In that situation you'd at least see growth within the Korean scene. But by isolating South Korea with region locking it drastically reduced the amount of exposure and tournaments a player could attend so interest in SC2 began to shrink within Korea, which is the only place it had any chance of thriving to begin with.

Anyhow, regardless of your opinion on how SC2 is being balanced. The original point i was trying to make was the audience for Overwatch & Starcraft are fundamentally different from one another in how they want their game developed.