It's the first few seconds after an engine has been off for hours (or worse, for potentially years) that are the problem.
That's very different from the start/stop feature they're talking about. That's about fully stopping the engine when you come to a complete stop like at a red light and then automatically starting again when you get off the brake.
Hearing regular start-stop on intersection gives me sorry feeling for the engine.
But they also start and stop way more than a gasoline-only car with stop-start. Because they stop and start repeatedly while driving too. Series hybrids even more so.
they do it very differently. My Prius never does that coughing sound that the start-stop engines frequently do. The powerful electric motor in Prius spins the engine to at least 1000rpm before fuel is injected. That way it is much easy on the engine and much more fuel efficient too.
This paper seems to say that generally they aren’t a problem. I’ve only seen unsubstantiated claims that they are one.