To answer your (new) point, not at all. I can fully understand why some individuals want to play only in Solo. I see no issue with any such reason except the ones I'm highlighting. ie: Powerplay actually rewarding CMDRS who choose to go into Solo, thus actively most likely making more CMDRs go to Solo.
And if we then consider ontop of this, Powerplay appears to be at times, community goals for different Powers/Factions to actively compete against each other, so to me it seems bizarre that goals can be actively rewarded, most likely to a greater degree, by CMDRs going "off rader" into Solo.
Do you not ultimately agree CMDRs in Solo will almost certainly (at the moment) have an easier and therefore more "effective" time for their Power/Faction? Do you not believe this will make many CMDRs choose Solo over Online? Consider my trading/blockade scenario for example. Why would a CMDR risk interdiction by a wing of CMDRs when simply choosing Solo means it will never happen. Of course some will, but I would suggest many simply will not.
It does make you wonder about what other people have proposed. When you start a slot you choose Online or Solo (or Group) and that's it. The two universes are completely autonomous. You are either playing in the Online Universe or the Solo (Group) one (for the life of that slot). I've not been in favour of it, but the more I think about Powerplay, the more credence I give that suggestion.