>find upgrade
>have to remember exactly which of the hundreds of active gates were locked by that specific upgrade (remember you can't make notes on the map, and there are only five map markers that you have to pay for each one)
>even if you know exactly which paths were opened by this upgrade, they are all spread to complete opposite corners of the map so you have to do a big giant fucking loop around the whole map hitting up each of the dozen different gates
>if you dare die even a single time while doing this big boring slog around the map, you will be lose a ton of progress and all your money
>going to retrieve this money wastes even more fucking time, and if you die again while on your way, then you permanently lose that money and wasted your time for nothing
>10/12 of these paths will be completely worthless garbage like a merchant that sells a couple items, a lore tidbit, a shortcut with no cutback, a rotten egg, a bit of geo, or a grubworm (read: a bit of geo)
>1/12 might be an actual somewhat useful merchant or upgrade
>1/12 is a critical upgrade that opens new paths
>repeat this tedious slog for every single new key upgrade you find.
I just fucking love modern metroidvania design!