The concern is that at max difficulty people will choose the easiest and/or fastest stronghold to run at said difficulty and ignore all the others. Having specific loot drops tied to specific strongholds is one way people imagine keeping stronghold variety but that introduces a ton of its own issues. All stronghold specific pieces would need to be desirable enough to multiple Javelins to promote a healthy mixed squad queuing for all strongholds. Hopefully there is already some system in place to alleviate this issue.