AAQ, also we have times when rishonim wrote things that were interpreted to be intended only for their time snd audience; many hold that the rambam wrote that there is no such thing as kishuf and sheidim to get jews away from such things that were culturally widespread in Egypt; the rambaN dismisses medrashim in his debates with Christians, while his actions were understood to only be permitted in that context
It’s not an issue of “convenience”, it’s an issue of, is this sefer going against pashut pshat and mesora from chazal? If it is, then we are open to exterior explanations… it’s not to fit some yeshivishe myopia as modern people claim. If chazal and rishonim say that the world is 5781 years old, then anything else we find should be made to comport with that, not the other way around. If chaz say that hashavas aveida stam is assur, and one sefer says a wild chidush that it’s not because of the way you learn the sugya normally; i.e. they’re automatically meyayesh because goyim dont return lost items al pi rov, or because of hafksras mamonam, or other pshatim, but a wild chidush that it’s only because they wouldn’t return ours….you can ask a ton of kashas on that pshat; why would the halacha of ownership and gezel depend on their attitude towards us? If one person steals, it doesn’t mean you can steal from him
Saying that it was a necessary contrivance is the more reasonable assumption