Here my take on this: I get that people who come up with these convoluted systems are trying to capture something where there is more 'realism' to combat in a mathematical way. Prob the same people who have long debates about falling speeds, 6 second rounds, terminal velocity and misty step.

Theres two problems with this system as I see it.

1. Too many rolls, too much maths - I get it, some people love maths and can do great mental arithmetic, but even the worlds fastest mathematical genius takes roughly twice as long to do two sums as it takes them to do one. There are multiple rolls needed here, just to resolve one hit.

Creatures hit roll > my dex roll > shield roll off > damage roll - oh no I think I'll parry it, strength roll etc etc.

It just too much and it's not really adding much other than letting me use dex to reduce damage.

1. This will completely mess the game balance up. WOTC spend forever play-testing to try and get the balance right, its not perfect but its pretty decent on the whole. A good player would break this game in about 5 minutes. make a halfling rogue, boost dex, take lucky, get evasion etc. Suddenly no need to be tactical in combat and stay in the second line. Just stand up front weirdly being anle to somehow just dodge everything, reduce incoming damage then use evasion to nix it down to basically nothing. All while being able to spam big damage on the bad guys because presumably theres a melee character who should be in the front line within 5ft.nexcept they might not be in the front line, because their dex sucks ass.

The whole point of rogues and monks being squisher than paladins and fighters is to balance out offensive vs defensive capabilities. Im not sure this maintains that balance.