What economy? The only economy in Animal Crossing is the one that you want to make. If you want to play the stalk market every week and travel to towns where turnips are selling for 450ish bells each you can do that legitimately, you don't need to save scum to do that. There won't be any hacking effecting your game since you need the current firmware and NSO online to interact online, no one's going to waste their money and get banned just to drop rare items in people's towns. Other people doing that stuff has zero way to effect you as a player unless you actively allow it to by inviting people to your town and accepting anything they give you. Unless they added a bunch of market house stuff, which I highly doubt, there's no defensible reason not to allow cloud saves.
This mindset goes completely against the philosophy of Animal Crossing for me, it's all about playing in whatever way makes you happy and you shouldn't feel compelled to compete in the rat race or feel left behind by what another player chooses to do. If that was my attitude towards the game, I never would have played New Leaf since the Japanese players already did everything before I could even start. People will still do that without cloud saves, so it's not like removing them really solves anything anyway. It just means that when your Switch breaks you're going to go through that same needless tragedy that Animal Crossing players have been going through for years now
I hope they make it so that Joan only buys turnips if you are a resident of that town to prevent online stalk marketing.
The amount of exploit money in the marketplace drives prices up. Sure you can play the game without interacting in trading, but I personally find it more fun to engage in trading, without the stalk market invalidating most of the money making schemes in the game. I remember playing the GCN game and having fun fishing for hours on end to pay off debt--this was before I was aware of the built in codes. Fishing was more fun when it was profitable relative to other options.
Also, I never said that this is worth removing cloud saves altogether. I'm just pointing out that just because there is a rationale behind a decision that is ultimately bad doesn't mean the rationale itself is unimportant. In Splatoon 1, it was very important for the health of the game that people do not save scum their ranks, but it was very easy to do so. In Splatoon 2, they got rid of save manipulation to prevent this, along with gear save scum, making it difficult outside of going full-hacker. However, preventing cloud saves because of this was a terrible compromise; The preferable solution was to store ranks server side. Now that doesn't mean that the reason behind the change wasn't important; the integrity of the ranking system is as important as ever for match making.
From your response, I notice 2 things on which I probably disagree with you.
1.I believe that players don't have the complete freedom to enjoy the game in they way they prefer when things are unbalanced. The expected values of various decisions actively shape how one feels about making said decisions. If removing an option (such as time traveling) can lift the temptation and pressure of unequal playing ground and make the experience more enjoyable to more people, as I believe it will, then it is a good change.
2. I also believe that players often times don't know how to make the game maximally enjoyable to them. It's the developer's job to steer them. When given too much leeway, players often follow the path of least resistance to an unfavorable end (and I mean unfavorable with respect to the player's own sensibilities). I believe this because many times in my gaming career, I've been forced to endure a 'bad' mechanic long enough to completely change my mind.