Can new players afford to leave endless pages of trades on the market? Probably not because they're limited on goods, Are you posting trades or just complaining no one else did? When I started new servers I found it more likely that players will take your trade even if the markets empty as it's there to trade.
That's just how the game is at start, and as mentioned several times now there are already things in place, guilds/friends list to help with goods when required. It's just for some reason you don't want to accept they are there because it doesn't aid your idea.
I think the simplest solution would be to change the default NPC Merchant Rate to 1:3 and scrap the corresponding Friends Tavern boost(s).
Obviously it wouldn't make player-made trades more available like the OP wants, but it would at least make the NPC trades more user-friendly.
The problem the OP is bringing up is definitely a problem, but it's also something that needs to be clearly defined in order for a effective solution to be made that doesn't just upset everyone once implemented. This is not a black and white issue of "just separate all inactives". You take out the inactive accounts. Great, now what? A lot of players like to have control of keeping the inactives on their Friend / Guild lists for sentimental reasons. The idea needs to be investigated in length with a UX designer type role to explore all options. I think while the OP is pointing to a issue that needs addressing, they're most likely approaching it from the wrong direction when it comes to a viable solution.
Realistically I think any real solution that involves looking for active players to trade with would require overhauling the Market interface and changing it from Social-Connections to World-Wide. Then anything else that needs addressing in regards to inactivity needs looking at with its own separate solutions as each area of inactivity has its own underlying root cause behind it.
The way the market is set up makes sense for the environment it was originally designed for. But it makes a lot less sense now due to the flood of Event buildings and subsequently less need to trade. A over-hauled market place would need to stack duplicate trades by User, have a greater array of filters available, and if possible take up more or less the whole screen (vertically) so you can fit as many trades on the screen as your monitor has room for.