No class has issues getting groups for 5 mans. Every class does bring something that is beneficial and for the MOST part hybrids issue with dps is that they oom way too quickly. Shadow priests, moonkins, ele shamans all do decent dps in 5 mans because the fights are much, much shorter.
From my experience playing vanilla for the last couple years or so, the min/max mentality doesn’t exist like it does on retail, sure there will be some people who nerd out but the majority of players will invite you no matter what.