All boons cheat?
Chronos and tempests/eles are capable of outputting a plethora of boons. It’s why you see basically perm quickness/protection and everything else. Hard to lock down one due to the others simply reapplying boons near instantly parallel to sustain/heals etc. 2000+ range? No, doubt it. Sounds like a regular organized group. Had a similar scenario take place last night at home camp enemy BL; a group of 4-5 players had constant bar of boons on them and the sustain was crazy. Fight lasted over 15 mins despite respawns coming in to fend them off.
5 mans can still be destructive; as portrayed in this gimmick of a clip: https://www.youtube.com/watch?v=wqwaNU6kwKI
Hope that helps answer your concern(s).
Your server’s reapers need to stop being useless and take some solid boon corruption. Nothing can save you + unholy feast + spiteful spirit
and watch them get crushed like bugs.