It’s up to the individual player to group. If they don’t, that’s not WM’s fault. But see end of my post for a suggestion.
That is just a player distribution in the zone and/or LfG issue. Players have choices in how they deal with it. A 5 party is enough for most of the time, but sometimes you need more. A rare for example is usually easy to get more to that location. Players have the tools available, if they don’t use or respond to them… that is on them.
It’s a multiplayer game, it’s designed for players to be social if they want to do better. It’s awesome that solo play is possible within a multiplayer game mode, but that’s the choice of those players. And they get the consequences, the chance of slightly slower questing, etc., however they are compensated with the WM bonus.
Bad analogy. War Mode is deliberately designed as it is. It’s perfectly playable and fit for purpose - WPvP with PvE on the side.
However… I did have an idea to help the PvEers. A slight extra PvE bonus for party grouping - not enough to encourage more PvEers into WM, just to group. I always suggest grouping but I know they won’t, they need a reward incentive. This could encourage grouping, but also present more challenge to WPvPers. There’ll still be some solo players for them that like killin those.