Ok I'll defend it.
SC2 doesn't really require defense. It is the most balanced RTS to date. I'll just let the graphs back that one up.
Balance report
Brood Wars requires a bit more defense. It isn't a perfectly balanced game and most will still argue it was balanced by circumstance, unintended bugs and still revolves around maps. But ignoring all that the win rates for the matchups still stay in the 60/40 realm. If one race needs is particularly struggling in Korea the map makers will make maps to favor them. Lately Terran has been the most powerful race during Brood Wars' resurgence in Korea but you could make a very easy argument that the fact is simply the Terran players are better and when a high accomplished Protoss (Bisu, Shuttle) actually play it shows the discrepancy isn't very large. There are just simply more high level Terran players.
Warcraft 3 TFT you could argue wasn't quite a pure RTS so it is difficult to determine some statistics. Due to the fact or RNG based item drops sometimes a map can be won or lost simply in the creep phase. Orc dominance is a pretty well known fact but lately it seems like there have been some meta shifts to deal with the blatant OP of the Grunt. If it is the most purely balanced RTS on the market that is probably false but all four races are still considered competitively viable even if UD is more of an afterthought (but can still work.) Finding modern win rates is nearly impossible since the only region actively playing WC3 is China and it is really hard to find any information out.
Now we'll move on to HotS. We still have to rely upon 3rd party information to figure out win rates but currently the highest winrate hero is TLV with 55.5%. The lowest winrate hero is Abathur 41.8%. Since the latter is mostly players just have no fucking clue what the hero is doing lets move to the second lowest which is Illidan at 44.1% (though you could make a similar argument for him.)
Lets compare that with it's competition. League shows Brand at 56% win rate at the highest and Azir at the lowest with 42%. The high/low are within enough margin I won't throw out the lowest like Abathur since the next lowest is only a 1% difference.
And then on to DOTA. #1 Omni with 60.75. Next is Abbadon with 59. Lowest is Oracle then Wisp with 40 and 40.5.
So if we're just taking pure win rates as an argument for balance HotS is no less and no more balanced than it's MOBA competition.
Then you can move on to other games. Is CSGO balanced? Hardly the same handful of guns are the only ones you ever reliably see.
Smite shows similar stuff where it is within the 60/40 balance realm.