The exceptions in the rules here for example are almost certainly directly constructed by Congress or anger from Congress and not particularly consistent with how the IRS expands laws by expanding existing theories if left alone:

https://www.irs.gov/businesses/small-businesses-self-employe...

Most IRS rulings and much of tax law itself are to try to patch over loopholes that are being exploited (the very page describes the various checks they have in place).