If such a planet is in orbit within the habitable zone of a Sun-like star, the X-ray/UV flux from the planet’s host star over billion-year timescales is too low to remove the planet’s hydrogen-helium envelope. However, things are different if such a planet is residing in the habitable zone of a red dwarf star. Since the luminosity of a star declines sharply with decreasing mass, a red dwarf star is many times less luminous than a Sun-like star. As a result, the habitable zone around a red dwarf star is situated much closer in, causing a planet in the habitable zone of a red dwarf star to be much nearer to its host star. Furthermore, red dwarf stars tend to be active and subject planets within their habitable zones to much higher X-ray/UV flux over billion year timescales.
The same process can remove an initial hydrogen-helium envelope comprising up to ~1 percent of the planet’s mass for a rocky planet with less than ~80 percent of the Earth’s mass residing at the outer edge of the habitable zone. Basically, a rocky planet in the habitable zone of a red dwarf star that is more massive than the Earth and has a hydrogen-helium envelope that makes up more than one percent of the planet’s mass cannot lose enough of its hydrogen-helium envelope to be habitable.
Low-mass planets are abundant around red dwarf stars, and red dwarf stars are the most common stars in the galaxy. If the evaporation of hydrogen-helium envelopes occurs readily for low-mass planets in the habitable zones around red dwarf stars, then red dwarf stars hosting planetary systems with habitable worlds could be a common phenomenon.
Owen & Mohanty (2016), “Habitability of Terrestrial-Mass Planets in the HZ of M Dwarfs. I. H/He-Dominated Atmospheres”, arXiv:1601.05143 [astro-ph.EP]