All you need to do is read this thread to see why the policy has changed. I didn't realize there were so many potential reasons to cancel an ADR at the last minute or not show.
I also don't see the big distinction so many are making in ADR hoarders & no shows. I agree the hoarders negatively affect us the customer more. From WDW's standpoint, an empty table is an empty table. It really doesn't matter to them why it's empty. The fact that it is costs them money. I'm sure they're just as interested in stopping the no shows as they are the hoarders.
It seems fairly obvious to me that they only want people who will definitely show up to their ADR, unless there's a serious illness or major injury, to make them. Most who are seriously ill won't care about losing $10/person. They'll be more concerned about their sick loved one. Anyone seriously injured on WDW property won't need to worry about cancellation fees. They will be taken care of. From my many years of going to WDW with people of all ages, I don't think either of these cases happen frequently to the large majority. They're definitely the exception not the rule.
It's the people who can foresee a dozen different reasons for cancelling at the last minute or not showing that they'd rather call for an ADR or walk-up, when they're 100% sure they'll be dining there. They want to fill the tables. From a business standpoint it makes more sense to fill them will walk-ups than with people who plan to show up, but may have something come up. Reasons, other than the 2 major ones above, are why most wouldn't show or they'd cancel at the last minute. Those are things that could be planned around, if they were give the importance a financial commitment usually receives. It may not be important to you, but it is to their bottom line. I can see why they wouldn't want people committing to ADRS, if they weren't going to plan their trip to assure they would definitely be at the restaurants at the appropriate time. If a guest wants more flexibility on vacation, or foresees potential problems, it's better for Disney, if they don't make ADRs. It's better to walk up, when everyone is hungry, well rested, feels good, etc. Unfortunately, life is about choices. Everyone needs to make the responsible one for their family, even if it's not the choice you'd prefer. I know I'd like to eat at 1/2 the restaurants on every trip, but I also know my stomach won't hold that much food. I hate having to choose what to keep & what to eliminate. It's not the fun choice, but it's the responsible one. (Darn responsibilities.

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I've read several times that people think to solve the problem they should just give tables away, if there's a no show. Think about that from a financial standpoint. For every 15 minutes a table sits empty, that's a 1/4th to 1/6th of a table turn (depending on how fast one eats). Multiply that by several tables & you're bleeding money. They want the tables turned as fast as they can be cleared. If they know the people with ADRs will definitely show, they then know how many walk-ups they can accept to accomplish that.
WDW has definitely done things in the past few years I don't agree with. In dining alone, I think the quality has declined while the prices continue to rise. To me, that's greed. However, people brought this policy change on themselves by making a commitment & not keeping it. If you don't want to commit to something 100%, you're better off not making the commitment at all. I can totally understand wanting more flexibility on vacation. Things do come up. If you can foresee that potentially happening, it probably makes more sense to book much less ADRs & do more walk-ups. If you owned the business, you could probably see you're not WDW's ideal ADR maker.
No offense to anyone.

It just seems obvious to me that WDW has probably heard the excuses given on this thread so many times they've decided they need to do something to eliminate them.