I find it funny that you're putting CS and Heroes of the Storm on the same level. Considering the latencies already mentioned (25-50ms to the closest AWS data center), CS should only be usable for casual play while for your other title... most Dota clones are playable up to 250-300ms latency, if you're not spiking.
Dota 2 is absolutely unplayable above 150 ms. Last-hitting and denying get hard enough, but at an even higher level you MUST be able to react to in-air projectiles with abilities such as Black King Bar, Manta Style, Blink, Naga's Mirror Image, etc to disjoint the projectiles.
Anecdotal evidence: historically I have a 60% winrate on US West servers (~40-70 ping) and only 50% winrate on US East servers (~110 ping). I've played on EU servers and it is absolutely miserable at 200+ ping. If I had to play regularly on anything above 110 and I'd probably drop to 45% or 40% winrate.
I've been playing Dota 1 and Dota 2 for 10 years now and I can tell you that with enough practice anything under 250ms is doable if there are no spikes in latency.
After a certain number of games you get used to it and start anticipating. It's not perfect, that's for sure, but it's definitely doable. Or are you talking about 5k+ MMR? In that case it is trickier, of course, but I know even pros managing to do it :)
Your blanket statement is false. Even professional teams playing online tournaments regularly deal with 200+ ms (EU vs. NA, etc.). It's not ideal, but playable.
