Once upon a time when an enclosure, m.2 to pcie adapter, used midrange GPU and semi-dodgy activation tool to play most games at high detail on the common resolution cost ~$200 together, it was a great option and the reduction in performance from the narrow bandwith & extra latency was surprisingly low.

A lot of the time you'd still be held back by affordable laptop CPUs being dual cores and the process being fiddly as hell provided you had the magic combination of good wiring, enough addressable memory to recognize the card, a card with a driver that would not forbit you this (I'm looking at you, NVIDIA) and no bios whitelisting on that m.2 port.

PCIe over thunderbolt made the process a lot easier, reliable and less likely to fry your laptops motherboard or set your dest on fire,, but $200+ just for the enclosure was just too much, esp since the fancy & slim laptops that'd you'd do this with still had very core and thermally limited CPUs most of the time.

Now it makes even less sense when a dedicated card makes up at least half of any decent builds cost & drivers are even more locked down, just people keep the buying the very lucrative, yet underperforming and misbadged mobile GPUs.