That's not moving goalposts, you're just arguing semantics. People generally think of eliminate when they say prevent in this kind of conversation....
If anything if they went "prevention" and not "eliminate" like in your sense...it would be even dumber because it would just make the steamdeck a more restrictive x86-processor computer compared to the systems people were already comparing it to up until it's release
Imagine how it would've gone down if people were saying "Of course you can do that, it's a PC" if people responded with "Yeah, except it's 10x harder to do things you could normally do on PC". They wanted it to be close to how a PC is, it was part of the advertising campaign.