Also, and I missed this at the time, it seems like Qualcomm was restricting manufacturers from also using competitors chips[2], although it seems the ruling was reversed on appeal [3], there's still evidence of restrictions. It would be unappealing to market an x86 device if it means losing access to Qualcomm cpus, especially in an era where Qualcomm modems were practically mandatory, so it makes sense that the only x86 (Asus Zenphone) I can think of is made by a company that didn't make a lot of phones.
Personally, I don't think the lack of app support would have been that much of a problem for sales of phones in the 2012 to 2016 time frame. If you got a couple hundred thousand phones out there, app developers would add support, because it wasn't too hard, a lot of developers were running x86 Android emulators, and they may have already had the x86 native code libraries and just didn't ship them because why bother when there's no phones.
Some of the first generation Asus Zenphone ran on x86, and it might have been rough for a while, but I think they sold reasonable numbers, and app developers started shipping x86 libraries. I don't know when Google Play added support for ABI specific APKs, maybe that was a factor too (if you have to have everything you support in the APK, then you'll be careful about what you support)
[1] https://www.pcworld.com/article/414673/intel-is-on-the-verge...
[2] https://www.cnn.com/2019/05/22/tech/qualcomm-antitrust/index...
[3] https://www.reuters.com/article/us-qualcomm-antitrust-idUSKC...