When issue arises, I do not think an average user will RMA the case (Mesh-Licious or other cases). An average joe would probably suspect a faulty motherboard or graphics card.
PS
How do you pronounce SSUPD? And my actual first thought sounded too much like 'stupid'.
They pronounce it Sunny Side Up in the video above, though ... where is the D in that? Can't say I get it, nor that I like the branding, but it's not like that matters much. Keeping the meshlicious name, though? I guess it's unique, but it's a poor choice IMO. Hard to say, doesn't sound good ... meh.
As for the average user not RMAing the case for that - not initially at least, I agree there. The issue then becomes them having a never-ending series of issues, never figuring out what is their problem, resulting in tons of frustration. Which will then be directed at the case once/if they actually figure this out. Unless they just sell it and move on, I guess.
The point being: this ins't a huge issue currently, but it is going to be one in 2021. There should at least be an option for a PCIe 4.0 compatible riser.