I had a few windows phones and it was not the lack of apps in my opinion, but a in a big part, a badly managed store policy that incentivized inflating numbers over actual apps. Searching for any term gave you 4/5 of trash, nonfunctional trash if you were lucky.

Discovery was fundamentally broken, if you had no good idea of what you where doing. Around 2014/2015 the ecosystem had pretty much no apps or at least functionality missing, besides snapchat and instagram (which was added at some point).