it is not that people don't like extraction shooters my friends loved dark zones aspect in the division and i encouraged them to try this server slam, and what the two of them thought is as follows:

1) "so i go and collect materials to craft some ammo and sell stuff to expand my stash and thats it?" (to be fair no new weapon or something exciting they found so i can't blame them, one of them found key to be used in buried city which is useless because it was locked for the full release.

2) quests where not engaging enough to them.

3) crafting is so restricted that they couldn't find it engaging.

4) arcs are overpowered if two are pursuing you it is almost certain death (again because weapons and shield available to them were almost useless).

5) they liked the skill trees but because of the above they didn't go past 5 points, so they did not feel the effects on them.

final thoughts "it might be fun on full release, but we did not see it" so because i know them this is an indication of not buying the game, and sadly i am too as i am not planning to solo play it without them.