For every topic there is a fitting episode of SMBC so here you go (spoilered because HUEG):
On top of the fact that making a game fun and enjoyable is pretty damn hard, there's another thing:
Games don't really contain a lot of new information, or require you to learn many new skills in order to play or progress. Not really. They have some lore (most of which is not essential), some rules, some rule-of-thumb maths involved, but the more crap you make
essential to the game the fewer people will play it. A game can have a bunch of hidden mechanics in the background but make the front end any more difficult than "use [thing] on [object]; repeat" and you lose 99% your audience. Pokemon is an example of a game with a whole bunch of statistics and probability and calculations in the background
SERIOUSLY WHAT THE FUCK IS THIS but 99.9% of the players will never ever know this, they'll be like "Pokeball go shakey shake".
Someone is bound to come up with examples of games that require you to memorize an encyclopedia or some other inane bullshit before you can even begin playing, so I will preemptively counter with the fact some people enjoy
gingering; there's all sorts out there but the majority will not go near it.
That is not to say you can't implement some educational elements into a game, you just can't have very many of them.
And it's not impossible to learn things through video games, but, again, it's a very tiny fraction of what that subject entails.
So an average edutainment game that can engage kids enough to actually play through it and retain some knowledge, can fit about one single lesson's worth of info on any given subject.
So multiply that by the number of lessons, and the number of subjects, and that's how many
high quality games you need to have if you want to have one school year's worth of edutainment.
And that's why educational games that by default and by design try to teach too much are invariably crap.