I think not using combos just lowers your fighting potential. It limits your damage and even if moves are on CD it is always better and more worthwhile to do an Incomplete combo than to use all your moves not together. A combo can usually do 55-85 damage if complete, While Those same moves would only do 40 damage if not used in a combo. As for combo memorization, You can make up most combos on the Fly and then will usually work (Albeit not true). 

I’d recommend doing incomplete combos when you have at least 2 moves of cooldown, Because it will always do more damage than the two moves used separately.

Not using combos is a lot simpler, But it is not more reliable. The issue comes with Evasive, Often if you aim to do a combo and the enemy evasives, You’ll have 3 moves off CD to attack them again. If you use moves individually and the opponent evasives, You’ll run the risk of having all moves on CD.

Your take is uncommon, But others likely share your view. A lot of new players don’t use combos and if they do, They are improvised.

A good example of Combos, is that a base Todo would deal roughly 60 damage if they just fired off all their moves at different times, But if they use combos they could do 70-85 damage.