They are. So here is a senario your focus firering on and advent cap with a total of 100 dps and their is a gardian absorbing 33% of that dps into it's own sheild.
Cap: say 3000 HP
Gardian: say 1300 HP
100 dps.
Not gardiand no regeneration calculation.
3000 / 100 = 30 seconds to kill the cap.
With gardian:
3000 / (100 - 100 x 0.33) = 38.96 so 39 seconds to kill the cap. But willt he 33 dps the gardian is absorbign kill it before the cap dies?
1300 / 33 = 39.39 so 39 second but a bit more. The gardian will barely survive this Assuming it was absobing damage the whole time.
Now lets add in 40% more damage on the cap via the designate target abilaty.
100 + 40% = 100 x 0.4 + 100 = 140
3000 / (140 - 140 x 0.33) = 31.98 so 32 seconds to kill the cap now. But the gardian was now taking 46.2 dps
so
1300 / 46.2 = 28.13 seconds so now the gardian dies before the cap so to find out how logn the cap will live we need to calculate how much hp it will have left when the gardian dies after 28 seconds
so
3000 - ((140 - 46.2) x 28) = 373.6 the cap will ahve 373.6 hp after the gardian dies fromt hsi point the cap is sufferign the 100% dmg formt he 140 dps so:
373.6 / 140 = 2.3 seconds add both times
28 + 2.6 = 30.6 so 31 seconds to kill the cap.
So To kill enemi cap without gardian and designate takes 30 seconds
With gardiand and no designate takes 39
with gardian and designate takes 31
So desigante target has indded given yout he frepower needed to punch throut the bonus that teh agrdian was giving him. How ever desigante target does no mean you will get to kill the cap or win the battle since many many MANY more factors come into play durring a real battle. How ever it will indeed help you get an edge back over your enemy.