I wouldn't call it a vibrant population but there are people that play during euro hours.
There are ways to advance your toons without raids but you won't get as far as raids, obviously. And the road is bumpy due to the spaced out nature of the content.
You can do 6man exp groups forever while also getting cash. There are a lot of AA's and tomes (similar to AA's) to put your exp into. You can spend the cash on good droppable gear which would put you in low-mid tier; I guess around tier 5-6 of the 13 available tiers.
Additionally there are PUGs that happen up to tier 9 content so you don't have to be in a regular raiding guild to fill out all your slots.
Look up charms as a place to put your cash. Its an item slot you buy from a vendor that can get bugger and bigger. You can see the available ones on the wiki. Selling an old charm gives you 99% of cost back as charm credit so its good use of money to improve your characters.
Some 6man specific zones:
Cmal 1-3: gear is worse than what you can buy but good stuff to wear until you have cash
Catacombs: gear is worse than what you can buy, decent to wear until you have cash
Hmal: some good specific slots, would still be challenging in all purchased gear
Emberflow: you can buy good droppable items from here and some good no drop items from mini bosses. But the no drop stuff from wing bosses are probably too hard to get without supplemented raid gear
Shadowdale treetops: no drop loot. would be rough to do without raid gear
Zones with best droppable loot: emberflow, citadel, bloody quarry, named undead in Remnants, first ruins.
Also as you level you should do Adept fights. Lower lever content meant for 1-2 groups; there's a pretty good support system of players to help these be killed. Just ask in game. Note: engaging these mobs is level restricted so look it up before you level
Finally there are a lot of quests to do! They can really help fill out your gear as you level and there are some big quests at high level. Vah quest, deity quest, main quest, heartlands faction quests.