Well there are tons of elements in BotG but you don't need to take them all into account. At least you didn't have to during the contest, i didn't play melee heroes afterwards.
Basically the game was and still is for the most part a back and fort; know when to move forward and attack, know when to move backwards. Done. - a lot of people went for simple heuristic bots btw, so clearly: NO, you didn't need a sim. Not to mention the melee bots that went full yolo for easy wins.
In CR you did have to take all elements or at least most of them into account. And it doesn't matter which game had more variables, what matters is how many you have to take into account to push forward. Without a sim you write foot long if conditions. A simulation takes that burden away.
Do i upgrade a tower when i have only 3 towers? Do i add a 3rd tower early on or try to escape? Do i build a barracks on top of the tower because there's lots of gold underneath it? Perhaps i can do that after the next wave? How do i ensure my queen doesn't get slowed down by my own knights, how do i make sure she doesn't get surrounded and die, how do i ... - i did spend a lot of time on CR too; i spent about as much time with trying to improve CR as i spent with trying to improve BotG btw. I did warn about the difficulties, but maybe it is indeed just a matter of opinion in both cases.
There's an awful lot more different aspects and variables to take into consideration. When this is the case a sim makes life much easier, so that's when you need it.
You DO need a sim in an asymmetric game, always, because otherwise you would have to account for two different types of starting positions. A sim takes care of that for you.
The asymmetry wasn't even obvious to most. There were two types. Half way in people were still stumbling on this revelation. So understanding all the rules wasn't that simple.
Memorizing strats instead of generalizing is also a solution and sure some people went for the cheese or an accidental good strat, but these strats were also harder to write up and manage in CR.
I already pointed out the rest of the difficult aspects of the game. Not going to relist every single one of them. But those points do stand, they were not refuted and they are what made the game hard. Pathing and collisions required a sim, queen gets stuck, queen gets slowed down. Oops i did repeat myself.
Also I didn't see anyone here brag they reached top 5 with heuristics alone. I didn't see anyone complain it was too easy to get into top 20. And even that alone makes a difference.
To be fair, the best measure would be to take into account what a heuristic for BotG and for CR would look like in comparison to a sim for BotG and CR. You compare all 4 bots and i am sure then it's pretty clear where the biggest difficulties lie.
P.S: Even getting gold was harder in CR, check some player contest ranks for both games.
Oh and CR creators had a smart trick i wish we also used: - hide the expert rules until bronze! That was actually a genius decision.
Meanwhile we briefly took this same idea into consideration before BotG launch and then dismissed it as a stupid idea.