Tanker damage is already less than half of brute damage which is ridiculous and unbalanced. nobody is asking for tankers to do the same damage, but if they dont do more damage than they currently do then it remains that tankers are balanced poorly and are un fun to play outside group settings. an important consideration of MMO design is solability, yes. becuase nobody is going to team 100% of the time, at least for sure not most people. My experience in FFXIV has taught me that tanks can hit hard and still be balanced with the dps. a tank in that game hits about half as hard as an equally well geared and played dps and it makes being a tank fun, becuase you're not a glorified meat shield, you can hurt things. Pretending tanks dont need to do damage is just as ridiculous as pretending support dont. Damage is THE MOST BASIC element of all gameplay in an mmo and thus is everybodies job. the people specialized for it more so than others.
Tankers have the same resist cap as brutes and only roughly 300 more HP yet brutes do double the damage if not more. this is NOT balanced nor can it be claimed to be close. Lower brute resist cap to 80% or fix tanker damage. only 2 options which address the issue.