Nowadays "several gigabytes" can also be read as "almost a percent" for a 1TB disk, which for an app so central is not outrageous to me. Well maybe it could be less for smaller 256G disks.
Right now, today, Apple will sell you a brand new phone with only 64GB of storage. And that's for users whose budget stretches to a brand new iphone - plenty of people spend less.
The modern web isn't just for people browsing from high-spec workstations and gaming PCs.