Flurry of Blows is worth 1/4 of a Level 1 Spell Slot, so one Divine Smite is the equivalent of 4 uses of Flurry of Blows, in terms of resources available to the respective Classes.
Right...
So, what happens at level 11 when Paladins get a permant +1/2 spell slot on every single attack they make forever? Does that get balanced out by the monk... in ANY possible way?
And, also, just to be fair and balanced TM, you do understand the fundamental problem with the design, right? Let's assume you are right and every divine smite dealing +2d8 damage is worth the same as the monk getting +1d6+mod (which it isn't, because the monk doesn't get a +6 modifier to their damage), the monk cannot flurry multiple times a turn.
Let's pick level 9. A paladin is going to be able to deal, in theory, 25d8, divide by half, and I'll round down, that is twelve uses of Divine Smite approximately. Which means the monk needs to use Flurry 48 times (12 x 4 = 48) [Also, this is assuming the old 2014 paladin, because an One DnD paladin gets a free 3rd level smite on top of that, meaning the monk would need about another EIGHT flurries]
Firstly, to use Flurry 48 times would require AT MINIMUM three short rests, because the monk only has 9 ki. A standard adventuring day assumes two short rests. So, we are resting more than the expected average AND using no other abilities (shockingly, paladins still have other abilities even if they use all their spells to smite). Additionally, most combats are easy to assume take about three rounds. At 48 rounds, you are looking at Eight combats, which is HIGH since most real games only have about four combats at most.
AND THEN, on top of ALL OF THAT, you have another fundamental problem. Divine Smite never misses. It is NEVER wasted. Flurry of Blows can miss. If you only hit with one of the two attacks, you might as well have not used the ki, because you gained no benefit over your normal turns.
So, again, Monks are in trouble. Yes, from levels 1 thru 4 they do good damage because of that bonus action attack. And at level 5 they can still mostly keep pace, but they fall off FAST and HARD.