The lead-generation criticism is fair, and sellers are right to notice it. An open house does put an agent in front of dozens of potential future clients who are not buying your house, and that benefit accrues to the agent hosting it whether or not your home sells that weekend.
That does not make it worthless for the seller. Extra foot traffic can surface a buyer who was not actively searching online, and a strong turnout can create urgency among buyers already circling the listing, especially during the first 2 to 3 weeks it is live.
The honest measure is whether it is paired with real marketing, not held instead of it. Get your hand-reviewed valuation from Joel Dyck.