Hmmm that makes sense the Polymers in gels pull the hair together, a gel that more watered down and includes humectants probably can't do that as efficiently. The one positive thing I got out of CIAB was knowing my hair loves my gels watered down. I dilute my current one as I apply it. Also, gels aren't like creams for me. The majority of the gel evaporates, so most "heavy" gels dry light anyway. A heavy cream, is a heavy cream.
I wouldn't get to caught up in the gel label. Some gels, especially the natural ones, are labeled strong hold and aren't. Some like PP are considered light-medium, but have strong hold...at least in my personal experience. It's best to read reviews to get a better idea of hold. Unfortunately it's almost impossible to tell by ingredients. Most gels have their ingredients in similar order. The quantities don't differ enough to change the list.