I've been playing a few alts and secondary specs recently. One interesting thing is all specializations appear to have a baseline build where you just take the left-hand side talents. These talents are all passives, and the resulting builds are actually really fun.
They are all focused on the core elements of the specialization. This type of build may not be the highest performing build, but they're simple and easy to use. They're probably a little too simple for someone's main spec, but I think they're perfect for alts or specs that you rarely play. Or even for weaker players.
For example, I was in a group for timewalking, and we needed a tank. Tanking is my least-played specialization. I hadn't actually tanked anything yet this expansion, though I had been picking up Azerite pieces and weapons. But I grabbed all the left talents and gave tanking timewalking dungeons a whirl. And it worked very well. That build was easy to play, and did a good enough job.
I did a similar experiment with my tank-spec demon hunter that I've started to level in BfA. The "all-left" build is quite fun. Fast leaps with flame crashes automatically adding Sigils is quite good while levelling.
Once again, though, these builds generally have one or two main buttons less than a regular build. This is good for weaker players, or less played classes/specs, because you don't have to remember how everything works. However, they're only "good enough", and are probably not strong enough for heroic raiding or mythic+.