Typing /help alone returns every possible argument combination for every existing command, which not only throws way too much information at the player at once, but doesn't even fit in the chat history in its whole (the farthest you can scroll back up is until around /stopsound).

In many cases, even typing /help followed by a valid command returns redundant information, e.g. /help gamerule returns every single gamerule name twice, one alone and one followed by the <value> argument. This is in fact the most detailed it can go, but that's too detailed – it could be simplified in order to make it easier to assimilate, and also easier on the eyes.

I'm aware that it ended up this way due to the new engine's implementation, but the /help command is rendered more unhelpful than anything when it just outputs so much information at once (instead of figuring out what the player is looking for and returning just what they need).

I'm not sure how its output could be improved, but an option is to implement a more general syntax for every command, like they were previously. That would work perfectly in conjunction with the dynamic argument completion – the syntax help would return a single or few lines containing the general command syntax (e.g. /gamerule <rule>), and the dynamic completion, on the other hand, would display deeper and more specific info about each argument (e.g. each individual gamerule name).