This, the only times I have used this were to patch over other bad decisions like maintaining 3-4 active releases of a SAAS product simultaneously or other decisions that forced us into a complex branching scheme. If you fix the downstream and upstream issues, you can usually simplify down to an easier branching model but if you are managing hotfixes and releases across many versions this works and keeps it sanish.
My last job was COTS where we still sent out physical DVDs to customers (because some were on air-gapped computers) so we weren't just maintaining LTS branches but had to actually make patch installers for all of them. A big benefit was that we could put the specific releng stuff in each specific branch (HEAD never had any releng and it got put on every release branch).
