Here's the thing you guys need to understand. Let's look at the actual step by step process in detail. Not that it's complicated mind you.
1.
Fully charge a side smash. (This right here screams "Please punish me!" The tiniest hit or grab will instantly interrupt the charge and potentially start a combo. So you'll only be able to attempt set this up during the time period both players of the opposing team have been either incapacitated or forced far off the stage.)
2.
In the window of time after the bowling ball is full charged, but before it vanishes, the other villager must pocket it. (This is a small window and requires both villagers to be close to one another in order to pull it off. Again, if either one of them is attacked during this, the setup will fail. It's easy to interrupt a process that leaves you so vulnerable to attack.
3.
Use it. (Because it's both slower than other FS and a short ranged projectile to boot it can only be used in specific situations. It's still subject to a projectile's downsides, but lacks its largest advantage. That being range. Did you know for example that Rosalina can hit Megaman with his own FS which has properties not unlike Villager's FS?)
It's easy to set this up when no one is attacking/pressuring you. You'd need to be dominating and in control of the match just to get a chance at it. You think players are going to just sit there and let you fully charge a smash and not make you pay for it?
*Important note about the Villager's Pocket - Doug Bensimon -
It seems you lose the stored projectile if you take enough damage; enough damage being a small amount considering how easily Villager kept dropping that baseball bat I had stored.
So even if you do manage to pocket a powerful object, you have to be very careful or you'll lose it. The longer you hold onto said object, the higher the risk of losing it becomes. Considering this along with the the sheer level of vulnerability setting this combo puts you in, actually executing it against a competent team will be a daunting task.