Help me convince a friend of the flexibility of PoE classes

I don't think you play the whole game if you slavishly copy someone who found out an optimal way to utilise skills and items. It is quite engaging to do these steps yourself, and see what your choices brought you. You might not have the most DPS and defense, but you are looking at the whole game instead of a narrow path.

This is not to say you should not ask or accept criticism, but if you're wondering about flexibility while just choosing a single predefined path, you have an odd way playing.

The defenition of viability is interesting as well, do you only view the single best way to clear maps as viable, or do you see any build that gives you an entertaining time as viable.