Not being clever after the fact (I have podcast evidence to prove it), but I was always baffled by how - on one hand, I could be listening to the Arsecast Extra and listen to James and Andrew dismissing Nelson's chances out of hand whilst simultaneously bemoaning our lack of depth on the wing. Arteta has always been very explicit about how highly he regards Reiss, it was just a case of Nelson being able to put it together.
If you take it as extremely unlikely you're going to be able to find another winger like Bukayo Saka to come and provide cover for him, then that leaves you with someone like Reiss Nelson. In a way, it makes more sense having him as cover (for either flank) than it would have to sign Mudryk for £100m and then have to choose between him and Martinelli every week.