These days, it's a good selling tool just as a KBB, NADA, Edmunds, CR pricing report. CARFAx even has a section on their site to help one find the value/pricing of a vehicle.
Also, it's doesn't matter if any of us think a CARFAx(AutoCheck is another source) is of any value, it's what other think and that's more important. Many potential buyers may in fact just walk away.
I/we just sold our daughter's car and I spent the money to get the "IMPORTANT" information from CARFAx(not the free stuff that's of no value) just so the car would move out of my driveway. Otherwise, this could have taken a couple of months instead of the 4 weeks that it actually took to sell this car. And we/she got a decent price for her car!
This is how I look at it. The CARFAx Vehicle History Report stays with a vehicle for it's whole life. So if I buy a used car with a clean CARFAx Report(regardless of what the previous owner did/didn't do), and I sell it years later with current "clean" CARFAx (regardless of what I did/didn't do), then again, this clean report stays with the vehicle and is a good selling tool.
The CARFAx Report can also show "Open Recalls" & recorded maintenance(not DIY maint). But, I guess we as DIYers can actually update our own vehicle history into the CARFAx Report? There is another thread on this but, no instructions on how it is done/performed. I'd like to learn this!