I never liked the idea of them and I always have found them problematic. When I first tried to use them my Nalegens tended to fall. Guessing they got squeezed up and out as I moved with them, sat down or bent over.

One laptop backpack I had for work (used to travel about 45 weeks a year for many years) had them and I lost a water bottle, countless soda bottles and a few snack bars, usually on a plane where it was stuffed under the seat in front of me.

It has gotten to the point where I will only use them if I'm willing to lose what I put in them and I generally am not willing to lose anything anymore.

High Sierra used to make a large laptop backpack that had tall/deep zippered side pockets but they would only last me a year and after going through two, at + $100 each, I relented and moved to a Swiss gear pack that had the two zippered side pockets in lieu of the netting pockets, but those were about 30% smaller and barely fit a 24oz bottle.

I had to look quite a while to find zippered side pocket in a laptop bag and rarely see them in a BOB-type pack.

If anyone has good suggestions, please share.