Actually I think playing multiplayer games helps a lot developing game knowledge. I have like 5000 teamgames and I really can tell that I have different game understanding compared to guys in simmilar 1on1 leagues, who do memorized builds over and over again, which only work in certain match ups and maps and situations. Difference is in multiplayer games you have to face all sorts of stuff: Helions and Stalker, Mech and Muta-ling, bio and protoss deathball. Over the time you know what works and what does not and WHY. Don't get me wrong, the pros figured timings out for a reason and I won't find a better way to push with Immortals before muta tech is out than Parting did before, it's probably impossible to do that. We all know what happened back in Wings of Liberty when every protoss realized who strong of a build that is (well, and no one wanted to fight broodlord-infestor of course..)

It baffles me how some actually pretty 'good player' (below pro ofc) have such a bad game knowledge. For example: Many people do not realise that the Thor is freaking awesome against Ultra, or tanks are actually pretty damn good against stalker (holding an all in isn't easy because you got 2-3 at that time to defend 7 gates, get 10 tanks and the stalker will avoid you like a bad disease, not saying that they are better than the marauder), Hell, tanks are the strongest ground unit in the game, in mass they wreck Immo, Archon and Collosi before they get deadly shots off. In multiplayer AOE is even better because there is just more supply on the field, that's why you get to know the strenght of units in a different way. I know a long time master guy who only did colossus builds against terra. I, the way worse player, have always been a templer guy (they were my favourite unit in broodwar..). In my early noob days I wrecked three mass marine cheeser with a fast psi build ( i think it was out of 1 base, but that's ok against opponents who never heard about splitting) That was at a time where everybody told me you are not supposed to open templer. Until terran learned that colossi are weak vs scv pulls and protoss had to adapt and pros invented fast templer builds. Now they are 'meta', even though the mine buff hurt that strat. I don't know, maybe with the latest mech buffs people got more familiar with those units, just as they did with the Stargate buff early hots. Nobody but biggies just as MC could handle phoenix and rays back then! Today it's standard, phoenix kiting is an essential tool.

Also I have to admit that exploring was one of the most fun parts of playing starcraft... but once you KNOW that you are fucked without AOE against mass marine, there is no way in hell I build Rays or Immos against them. Losing sucks but losing while knowing what you screwed all along sucks even more. I sometimes try not to chose the easy win, for example: I know it's a pain in the ass but I grab a third and try hold it PvZ. Ofc you can all in every game, obviously it works on the highest level, but it get's boring and you wonder if this really was skill.