Looking at the whole issue through resource managment optic, both MCM and multipath are extremely inferior to notching.
Because in either case youre giving up much more valuable resource to take out the enemy missile - in case of MCM youre giving up your own missiles, and in case of multipath, you give up positioning (or to much larger degree than you do with notch).
With notch you just give up what, ever so slightly of your energy/positioning by entering notch for the first time and some chaff.
Suppose youre flying EFT with 8x ARHs and 2x IRs and you get drop on enemy GE. You start your attack. GE turns in and starts MCMing your missiles. Lets assume he doesnt attack and focuses on shooting down your missiles first. Lets assume 100% interception rate.
What inevitably happens is that youre down to your IRs while GE still has 4 ARHs left.
Allright lets suppose he now starts to attack. And lets assume through sheer size of your manhood and skill you intercept two of his ARHs with your IRs.
He still has two ARHs coming your way, and you, tarnished, appear to be missileless. And unless youre just that good to intercept mach 1 missile with your guns, you still have to enter notch or die.
Compare that to notching in the first place where you can sit however long you like and expend only few bursts of your chaff. GE can only hopelessly sit in his cuck throne since he has no means of engaging you.
What will he do? Go for gun kill? In F-15 vs EFT? Yeah good luck. Go full defensive and sit in notch on his own? Cool, since he has no means to threaten you you eventually park your plane directly on his six and perform colonoscopy with 9M. If he doesnt run out of fuel first. Run towards base to land and repair? He just gave up all of his positioning, for which reward is death.
“Oh he will just multipath!”
Excelent transition to the other half of the issue I say.
By multipathing, he effectively limits his manuevering to 2D plane (since he would have to leave the multipath to utilize the y axis. He also limits his speed greatly because I doubt anyone is that good to fly nap of the earth at mach 1.6 (i doubt that any plane is even capable of doing it without folding like badly put together ikea furniture). Lower speed combined with thicker air means less range, since his missiles now have to burn most of their energy to climb to you.
“But my missiles wont hit him due to multipath”
Astute observation, except since you have all of the positioning advantage over him you can eat, whats stopping you from just dunking on him with IR which doesnt care about MP? Even if you were limited to ARHs only, they can still hit multipathing targets if coming from steep enough angle. Remember how youre still sitting at alt when the enemy is crawling along the multipath alt? Yeah.
I dont have clip at hand of this being out into practise since i never figured out id need it but i can provide one tommorow as i will be grinding the star, since this happens all the time.
To conclude, notch is the superior tactic, and by not doing it youre just limiting yourself.