Sometimes it is exactly right. The mistake is doing it by default rather than by decision.
Selling as-is means you are not undertaking repairs or improvements before listing, and generally not agreeing to them after an inspection either. It does not mean you can withhold what you know. Disclosure obligations apply regardless, and "as-is" is not a shield for a known material defect.
Be clear-eyed: as-is narrows your buyer pool substantially. You lose most buyers who need a mortgage on a move-in-ready home and want to unpack rather than renovate. What remains is investors, renovators and bargain hunters — and they are, by definition, looking for a discount.
You should expect that discount to exceed what the repairs would have cost. That is the trade, and it is often still worth making for the reasons above. It just should not be a surprise.
The version that works badly is as-is by neglect — an unprepared home at a move-in-ready price. The version that works is as-is by decision, priced honestly, presented cleanly, with the reasons understood.