It is not "seat tube height", it is seat tube length and then most of the other stuff above. Generally the most important measurement is the TT length but that would be too easy for most people so they use forty different ways to measure the seat tube and then you end up asking for help on a forum... and the circle of life is complete.
You are just wrong and fall into the trap of many on here that subscribe to the myth that top tube length is the most important parameter to fit. It isn't.
It is one of the most important but no more important than head tube length or seat tube angle. Most can't think in more than one dimension and why they fall into the trap of believing top tube angle dominates the hierarchy of fit. It is no more important than head tube length. Height of the handlebars is as important as horizontal reach as reach is comprised of both vertical and horizontal components. Further seat tube angle is hugely critical because it not only affects effective top tube length but rider CG on the bike influencing handling and even weight one carries on their hands independent of reach.
OP...you won't grasp all of the relationships but most over complicate fit for their first bike. As mentioned, .67 X cycling inseam will fit 95% of recreational cyclists just fine.
OP...if your cycling inseam really is 88.5 cm, then a 58 is a slightly racey fit and a 60 cm is more of comfort fit because it will afford higher handlebars. BTW....we have the same inseam...I am 6'1" and ride a 59 center to top of top tube which = 57 center to center which is how my bike frame is sized.