I have been pretty successful removing old paper from unprimed drywall. Of course, it has been easier if the drywall did have primer or 'sizing' on it before papering. Regarding that "enzyme crap", I have used Zinser DIF many times and consider it well worth using. (Disclaimer: No financial connection with Zinser or any other company- I'm just a satisfied customer). DIF has worked well enough for me that I use it always. I believe it is more effective than plain warm water alone. Hot water spray and/or steam is probably pretty good as an alternative. I'd be concerned about possible paper pulloff. YMMV. I prefer the enzyme.
Perforating the old paper is good practice, and repeatedly wetting the paper and keeping it wet makes a huge difference! Take your time and it will go much easier. Get in a rush, and you are definitely going to pull off some of the paper on the drywall. Not good.
OTOH I have probably never encountered a wallpaper installation where at least a few minor tears didn't happen to the drywall. At least I don't remember any. Minor drywall repairs after pulling wallpaper off are simply routine IMO. Besides, people who paper often conceal various drywall defects behind that paper. For paint, you can't tolerate them, so you have to fix them. Plan on at least a little minor patching.
I believe it's also important to continue to wet the now paperless drywall with DIF and carefully scrape off the sometimes thick glue layer that remains behind, using a stiff scraper. After the drywall has had overnight to dry out, a light sanding is also very much worth the time (removes any remaining glue and other defects- if you want high quality work). Leave that glue on there, get a crappy paint job. Your choice. Note that the job can thus take up to 3 days, allowing for overnight complete drying of the saturated paper on the drywall, then another night to allow conventional drywall 'mud' patches to dry. Sand and paint on the 3rd day. Of course, you absolutely can telescope the entire operation into a single day. There are various shortcut products and methods. I wouldn't do that, however. A little paper separation can happen whenever you wet drywall that much. You can see it better and you can mitigate it better after an overnight dry. Plastering over wet, separated drywall paper leads to hollow bulges after your drywall mud dries. Then you get to fix it a second time.
BTW I have done this job many times, mostly for others, and always get rave reviews about the quality of my painting. Cut corners, and you may not. You will always get better painting results if you have the patience to give the drywall overnight to dry out before going on- also sand- and prime as well, in almost every case. Although all this is optional, this is how to get the best results. I doubt many of the pro painter companies do this. Time is money in that business. Get that big sprayer out and lay it on there thick. But pray your paint supplier didn't just reformulate their paint last month to meet some new EPA VOC requirements. A real stomach turner is to watch paint applied too thick start to develop runs. That happened to me one time when I reluctantly agreed to use some 'customer specified' latex SG paint I wasn't familiar with. Then you get to run around catching those runs with a brush. Anyway, if you leave glue on the wall, you get a sandpaper texture, then you might try to lay the paint on thicker to cover that. Better: proper surface prep, primer coat(s), two roller coats of good quality paint.
It's all a tradeoff- you want it fast or you want it best? It all depends on how much patience the homeowner has for extended jobs. I was surprised that most folks I did this for wanted best. But some folks are definitely not painters. They hate painting, just want to get it over with.
:D
