May be I don't quite understand this - a "proper" employment based immigrant visa is one of https://travel.state.gov/content/travel/en/us-visas/immigrat.... Which is what most H1B folks apply for. Not sure how H1b is a backdoor for permanent residency.

Is your point that immigrant visa takes however long it takes (>10 years for Indians), and if one is already here on H1b, they should not expect H1b to be indefinitely extended until immigration visa is approved?

For pretty much all countries other than India, there are no practical issues, since they get permanent residence well before their H1b expires.

The problem is magnified for Indians to the extent that their lives are basically in suspended animation for several years