Remove content lockout and allow infinite runs of content but with no reward after the first run.
There are support mains in the game who literally only play support, some with 6 or more Bards or Paladins, but guess what ? They can only do 1 run of any content each week due to content lockout so rather than having a support player who would run 20x Valtan for example, you would need 20 support players who would run 1x each. Also, after the majority of supports have done their content runs, the amount of supports available for content near reset are almost non existent.
Of course, this solution isn’t without it’s own issues. Without content lockouts, the amount of “busses”(Players selling carries) would skyrocket and due to top end players being able to run content multiple times, the discrimination against players who don’t min/max would increase.(These things already happen but would simply be more prominent).
Despite the drawbacks, this is the only realistic solution to the lack of supports as currently any 1 support can only play with exactly 1 group and they are no longer a support for the entire week as they only have solo content available to them.