Console storage fills quickly and is awkward to expand. The restriction exists because current consoles treat storage as part of the rendering pipeline rather than as a place to keep files.
The drive is part of the performance specification
Modern consoles stream assets from storage during play rather than loading a whole level into memory first. The drive's speed therefore affects what can be drawn.
Developers can rely on a guaranteed transfer rate, which lets them build worlds that would not fit in memory and move through them without loading screens.
Because that guarantee applies to every machine, any expansion must meet the same standard. A slower drive would break the assumption games are built on.
Compression hardware sits in the path
Consoles include dedicated hardware to decompress data as it leaves storage, which multiplies effective throughput without using the main processor.
That block is designed around a specific compression format and expected input rate. Storage attached outside this path does not benefit from it.
This is why external drives are typically permitted for storing games but not for playing current-generation titles. The path, not the capacity, is the constraint.
Certified expansion is narrow by design
Where expansion is supported, the platform holder specifies acceptable drives by performance class rather than allowing anything that physically fits.
Heat is part of the specification too, since sustained transfer in a sealed console body is a harder thermal problem than the same drive in a desktop.
The narrow list frustrates buyers but preserves the guarantee. A machine where some games ran worse depending on which drive they occupied would undermine the platform's core promise.
Game sizes grew for storage-related reasons
Fast streaming encourages storing assets in forms optimised for reading rather than for compactness, including duplicated data arranged for locality.
The same design that removes loading screens therefore consumes capacity faster. The two properties are linked rather than coincidental.
Selective installation of modes and language packs is the main mitigation, and it is now common in large releases for exactly this reason.
Managing capacity has become part of ownership
Players delete and reinstall regularly, which shifts the cost from storage to bandwidth and time. For metered or slow connections that trade is poor.
Platforms mitigate this with archiving that keeps save data and entitlements while removing the installation, so reinstalling restores progress.
The underlying position is unlikely to change while storage speed remains a design assumption. Capacity is limited because the drive is doing a job that a larger, slower one could not.