The idea of a 4 in 1 bucket is this.
1: It works as a standard bucket for scooping loose material
2: It works as a bulldozer blade (well sort of) when the upper clamshell is raised up out of the way
3: It works as a scraper in the back dragging mode with a cutting edge on the back lower side of the bucket
4: It works sort of like a grapple with the clamshell opened up to grasp logs and rocks between the upper clamshell portion and the lower portion.
There are usually some "teeth" on the lower portion to help hold these logs or debris from slipping out.
You maybe could even argue that a 5th function is the dumping of loose material can be accomplished by opening the clamshell for a "bottom dump" instead of the normal scoop being turned downward into "dump" angle. This would kinda allow for possibly a higher height to clear the side of a dump truck without having to angle the scoop down.
In my analysis a 4 in 1 bucket does a bunch of things, and doesn't do any of them as well as a dedicated front implement. BUT it does it with just one tool that you always have with you. Sort of like a multitool. Is it as good of a screwdriver or wrench or even knife blade as a dedicated screwdriver, wrench or knife? No probably not, or at least not in all circumstances.
So you have to decide, is having a "multitool" with you all the time vs having dedicated tools the way you want to go? For some folks, yes, for others, no, not so much.