Can I just clarify.......what are they actually for...?
Bent large format tiles.
Uneven substrate .
To avoid lips due to adhesive shrinkage.
Any more ?
IMO they help straighten out bent large tiles, particular planks.
On a substrate that isn't perfectly flat you can have two tiles beside each other both with full coverage but there may be 1-2 mill of difference in height, by raising the low tile and pressing down on the high tile you split the difference and clamp it with a clip until the adhesive sets.
The same logic applies to adhesive shrinkage.
There are many other uses for them that you learn the more you use them, like clamping tiles above windows etc.
All of us professional tilers can lay tiles level with a solid bed, the correct use of clips simply speeds the process up with confidence that the tiles will be in the same place as you left them when you come back to grout them.
In the wrong hands they can of course lead to failures due to incorrect adhesive bedding etc, but a grinder in the wrong hands can be a disaster also.
For those of us who are defending they're use we are simply sharing what we find to be a positive advancement in tiling tools.
Personally my heart would sink at the thought of having to revert back to tilling large formats without them.