I don't get this topic.

I finished the game on tactician, which I found very challenging many times throughout, and I used respec once on all characters to fine tune them, some got it twice because of errors (changed Minsc to Str ranger then to Str ranger/barbarian).

What great advantage is there to be had by respec'cing?

I can think of finding heat/acuity/sparks magic items and respec'cing a companion to be proficient with a synergizing set of 3. However, in 2 more hours of play you'll get some item that's flat out better than the set power.

Some multi-classes are noticeably powerful at certain specific levels before falling back down into the power curve. So, there's a bump here and there, but that's only 1 in 4 of your characters. Plus 20% power for 25% of the party. I suppose you can leverage that to be more than overall +5%, good for you! You've taken the time to learn a niche build, so there's a little reward - for a while.

I just don't see the great advantage for the time spent respec'cing. What am I missing?