Legendary Armor Ranks question

What is the benefit of buying/making a Rank 4 armor vessel rather than just upgrading a Rank 1 vessel?

My understanding it that they both take the same amount of Soul Ash to reach the same goal of a finished 235 piece.

So isn’t it cheaper to just buy the 190 model and upgrade? Or is there some additional costs I’m not aware of?

There is no benefit as of the moment. Maybe when people have excess Soul Ash, making a 4 from the start would be logical.