>>How about learning how to alter or re-make clothing from your size range instead, as our grandparents and great-grandparents used to do when clothing was scarce and/or rationed?

It's a nice thought, but our grandparents and great-grandparents also strongly preferred to start with a larger size and work down in alterations. There's a reason really small clothes are much more common vintage and in museums too, and it's because most of the large size ones got cut down until they were either too tiny to cut down anymore or completely worn out.

That said I've seen some amazing plus-size thrifting blogs that combine multiple smaller pieces into one amazing large one, and our ancestors did do that too (it is more work though.)

Also LW does indeed need to fix their shitty attitude.