The issue with free draggables

Well, it can depend on the level. KPACABA's Libra used them perfectly, but I think he deleted it for some reason. Big Draggables can't go through small spaces, so you can use that to prevent it from activating the Win Block. I wouldn't recommend using them, though, as they're (for the most part) unpredictable (one of the exceptions is the Libra).

 

Even when they can't be used to shortcut the level they pose problems. The same goes for places where they are enshrined in other blocks. One case example is @Gepeto 's promising but glitchy Headache where it would easily come out of its housing. Some authors intend to have the players align free draggables through a hole, which is quite painful to do as they don't align well. Apart from the crude unpredictability of them, I've also seen examples of where they are hidden or just simply obscured from the logical path and the player is expected to make a conclusion that something illogical is required. Rather frustrating all around to the point for me that I've started to give up on levels such as @Ricko 's otherwise nice Coffin Mystery.

@Astral_Mage To answer your question directly, I believe they should be used under the following circumstances:
- there is no way that they could be used to trigger the end button directly or indirectly (say by flinging something)
- they are not intended to be slotted into hard places;
- they are restrained to a single block (or a plane of blocks) and not expected to leave their original plane.

The exception being where the author clearly articulates that the level is for playing around with free draggables just for the randomness factor - some people may like to goof around that way.

 

I appreciate your stance (and love your levels because of it). I would just change "solution" to "situation" in your quote.