The problem with AIA chasing is that it's a privacy violation. Not a huge one but enough to be completely unacceptable for say Mozilla.
In fetching the needed intermediates we reveal which intermediates we needed, if you're Let's Encrypt you operate only a few intermediates and you issue a truly astounding number of certificates from each so that's barely information, but if you're a small CA and you have say a dozen intermediates you absolutely could arrange for say pro-Party A sites to all use intermediate #6 while also pro-Party B sites used intermediate #8 and then use the resulting data from AIA chasing to measure who is going to "Party A" sites and direct political advertising at those people...
By employing mitigations/workarounds, they encourage misconfigured servers, and that in turn produces unexpected or inconsistent behaviors when interacting with those servers through different client types. eg you might see different behavior in FF vs Chrome, or Chrome vs curl/python, etc.
Thanks for explaining.