No! You can and hopefully will group in both rifts and greater rifts. There are separate leaderboard for solos and groups. Though some achievements and seasonal progression will require solo achievement.
Grouping can be awesome, as mentioned above, but when it comes to GRās, the sum is greater than the whole as group difficulty scales slightly differently - a 4 man GR does not mean mobs are 4x as hard - more like 2x, so as a group you can likely push higher than solo - better drops, more XP, easier to get gems higher levels. Even moreso with well crafted groups with complimentary builds. Zero DPS builds (ZDPS) exist solely to provide massive group buffs, or de-buffs, or pulls, etc, and allow some serious DPS, but squishy builds to do their thing.
A couple of seasons back, if you were a ZPDS monk, everyone wanted to be your friend!
I should also point out that itās fine to vary your build based on what you are doing at any given time. I talked about Nemesis Bracers yesterday, which spawn an elite pack when you click on a pylon/shrine. These massively reduce your rift/GR times as there are usually several pylons/shrines in any given run and the elites they spawn drop globes, which progress the meter faster. If you are farming for GR keys, or leveling gems for augments, Nemās are a mandatory build adjustment to save you time, as long as your mitigation remains viable. Itās better to run Nemās in TX rifts to farm keys, for example, than to run TXIII rifts for keys with no Nemās. When you are curb stomping GR60, but want to level some gems to 40 for augments, substituting mitigation bracers for Nemās at GR 50 is unlikely to be a death sentence for you, but will save you tons of time.
You may even vary legendary gems, depending on what you are doing. Bane of the Stricken is a waste during farming, replace it with Bane of the Powerful for faster clears. But you may need Stricken to kill that Guardian at GR65ā¦
Thank fuck for the armory, which makes this alterations much easier than in the past.