They're
technically the superior format for videogames. N64 era cartridge tech is competitive with some aspects of modern storage methods. However, they have as issues:
- lead time for production. cartridges take longer to make than discs.
- due to the lead time, first parties will insist you buy a lot (a LOT) of cartridges at once and you better hope you can sell them all. Not a problem for super popular games, but extremely risky if you're a small company.
- and the expense means games have to cost a lot to make back money.
If we could have all the benefits of cartridge with none of the downsides you would never see a developer willingly choose any other medium. There's a whole bunch of stuff where we have to deal with hdd read latency and all that crap that were not an issue in the home console cartridge era.