Honestly, Virgin Media don't put them in unless they absolutely need to.
For FTTP the optical fibre has no way of delivering power, and needs something to convert the light wave being sent down the fibre into an electrical signal that can then be sent over metal cable to the Hub.
All providers delivering FTTP have to do the same for the same reason.
But saying that, even where Virgin Media install an extra powered device in a coax install, it's needed to ensure that the signal to the home is within the levels required to work properly. Without the powered device you could see issues on broadband or TV.
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I work for Virgin Media - but all opinions posted here are my own