I appreciate contractor perspectives. I do find that there's sometimes a lack of shared perspective though, even between people who do new construction only vs reno. It's like yes, great that you can tape and mud an entire house with bare subfloor, no occupancy or finishes with only 3 guys and 10k in drywall tools and bang it out in a day... lol.
I wear many hats, new build houses isn't exactly something I've done a ton of vs work in other realms. Plenty of experience in commercial in that sense however. I have done a shitload of "renos", where we strip out everything old and shitty down to the frame if needed, and then rebuild. Restored old houses and buildings, where I had to learn seldom used skills such plastering and lathe, and we pretty much couldn't rip anything out, unless we could restore it the way it was. I've worked property management maint guy in shitty areas, with shitty tenants, where it was pointless to spend money, and the walls were mostly held together with cheap mud and cheap mesh tape, and using cheap paint from a recycler. Also been project manager, foreman, safety officer, and a sit on my ass and yawn all day brand new & clean looking White Hat wearing motherfucker too. I've also worked real Haz Mat work, even went to... Europe once to "consult" on air filters, even though I didn't end up doing a damn thing aside from a suggestion or 2 on safety. I've done work in government, finanacial and military sites I can't ever really discuss, not because there was anything at all secret or interesting, but because that's the way it is.
These days I'm mastering the skills of being half crippled, consequences of less than adequate financial planning in my youth, and some old age symptoms creeping up way faster than is typically normal for someone that is 44, before anyone thinks I'm tooting my horn too loudly here.
I wasn't pointing you out, at least didn't intend it, more the general conversation going on regarding, walls, ceilings, drywall, mud ect. My position has always been, if its old and shitty drywall/plaster, rip it out and save time, stress, and usally money in the shorter and longer term. I have no idea what you are actually dealing with without looking at it myself, same as I would tell any client. If you dealing with low tier rentals, just doing some simple "good enough" home repair/reno or spinning out quick renos where no one really gives a shit, none of that applies.
Hit us with those expensive methods and feel free to lecture! I like lecturing much more than the shitty wallpaper I've been putting off removing. I know I should probably just put up new sheetrock, but I'm lazy and some of the walls are still plaster/lath.
I've used some type of solvent in the past for wallpaper and/or paint layers. I can't recall what it was, even the chemical itself, it wasn't something off the shelf at home depot, and it wasn't cheap, to the point I recall us being extra cautious not to spill/waste it. We were using it to strip decades of paint/wallpaper/gunk/ect off old antique level wooden paneling, moulding, ect that needed to be preserved. If you were cautious on the final layers you could leave the original finish on the wood untouched. We would apply it multiple times, but it would just unbond everything, and you could scrape/pull sheets of both paint and paper off. While my experience is rip it the hell out, I can imagine some kind of process, albeit slower and more work, with a cheaper chemical that would give you a similar effect, perhaps even starting at a corner, and using a spray bottle and nice sharp scraper. If it's something that evaporates, it won't do much, or anything to the drywall paper if you don't go crazy.
Use one of these or something similar, to "aerate" your surface first before you apply:
This is an idea, not actual advice, but if I had to redo a wall at home, without replacing it, likely the way I'd try it first if it was stubborn paper/paint layers. Check what chemical the brand name wallpaper strippers use, and go buy the Tim Allen concentrated version from a local chem supply lol.