These jumper packs are all about convenience, and when needed they certainly are convenient, if they can do their job.
Some people act like they are a real battery though, and cycle them deeply powering USB devices or powering something with the built in inverter, instead of cycling their starter battery shallowly.
The chargers which come with these jumper packs are quite poor, and might never actually fully charge the abused Asian AGM inside. When needed, a jumper pack used for anything but the occasional jump start, might not have enough gusto to actually help the starter battery start the engine.
The tiny lithium jumper packs now available are certainly Neat, but unfortunately many people correlate their ability to help a weak L/A battery start a motor with super capacity as well, which these lithium jump packs just do not have.
I've managed to not purchase a lithium pocket jumpstarter. I do have occasion for a portable 12v source, but I can just get a Tiny AGM for a fraction of the price, and so far have resisted that purchase as well.
I've got a bunch of 18650 cells from an old laptop battery which theoretically could fulfill any portable ~12v needs I have, but I've never actually hooked the cells in series nor am I likely to.
I often see jumper packs put out with the trash. I've scavenged them for their cables and clamps, and keep the batteries to recycle when I need to purchase a new battery. I've offered to put a new battery in one nicer jump starter for the owner, but they could not be bothered and just ordered a new one, for 3x the price of just the battery alone.
Some people are so poor, all they have is money