>>14609582
>it provides the most valuable learning experience into making a game
That doesn't add merit to the game itself and is therefore only valuable to you, not the players.
Game based arguments would be features that engines usually lack but that are needed for some game mechanic you would like to implement (an example would be the xmoon game, where you actually shove a penis into a vagina and both are full physics-objects, which would make your average engine shit itself)
Alternatively, you could optimize performance through only including exactly what you need instead of having bloat attached.
That being said, making, debugging, and optimizing your own engine capable of handling >Y2k graphics is a major task even for experienced developers.
Unless you've already made a bunch of games and are very familiar with C/C++ and possibly Assembly, don't do it because it'll kill both your game and motivation.
>>14611272
That's why you use Godot, where you can access and change the source code at your leisure.
>>14612018
>Godot
>major flaws
Since you appear capable of fixing them, why not try that instead of whinging about it? It's Open Source for a reason.