What ? .. discourages?? Why??
Paul, since my father was one of the "acid rinse guys" in the 90's, I was particularly sensitive to this issue. (OK, defensive, actually)
What we've learned in the past 20 years in that neutralizing pH alone does not prevent resoiling, and that while some acid rinses help in the removal of pre-existing residues, others contribute to resoiling because they leave a sticky residue themselves.
It was also instructive to learn that none of the carpet manufacturers or synthetic fiber producers are willing to give a "desired pH reading" for what they want left on the carpet itself. They are even queasy about the "pH 10 rule", but let it go as a reasonable compromise and to attempt to keep things simple.
There is nothing wrong with using an acidic rinse agent if its formulated not to contribute to resoiling. Its especially helpful if you are moving back and forth from cleaning carpet and cleaning natural fiber upholstery.
But you don't
have to do it unless you are correcting a pH imbalance, attempting to stabilize dyes, or to prevent cellulose browning.
I feel like I hijacked the thread here, but I was just trying to show how what is heard in class isn't always what was meant to be said.