I think to have a reasonable discussion on Deterrence, it has to be operationally defined for the context of the discussion. The back and forth b/w the members has been because of their individual take on what deterrence mean. One side is taking it as an "absolute military superiority" (where India can never launch a strike at us) while the other side is taking it as an "attrition penalty" (where India can launch a strike but can't establish operational advantage).
IMPO (and admittedly a narrow one) - India probably thought their platform superiority (Rafale and S-400) gave them sufficient operational advantage to pick a conflict with Pakistan and continue to maintain operational advantage. It is evident from their tactics post May 7 (esp night of May 9/10) how they didn't have a contingency plan once their platform dependent bubble bursted. In an ideal timeline, India wouldn't have felt the need to use CMs (that was their last tier of weapons system below a nuclear threshold and a full-scale war).
The bolded part of you comment is the actual situation.
India was desperate to have "Save face"......and that's when they resorted to throwing everything at Pakistan to get a hit on airbases (which btw the shit kumars think 'destroyed the airbases completely') while no one mentions the total number of ALCM/SLCM and other SOWs that India launched and how many actually scored a hit, and out of those how many actual scored a hit of any real value in terms of the larger Air Operations of PAF? The answer is that the percentage would be in low single digits. Not at all a good number regardless of it being a short war.
Also, the off-ramp for de-escalation included Pakistan not displaying any BDA what so ever of its impact on India to let their hate filled awaam gasp on the damaged hangers aerial pictures and let it go.
Lets see what we get out of it, we successfully tracked each and every one of their SOWs, right?
We took of most of them out via soft or hard kills, right?
So pretty much we know how to plug the gaps now and above all, exact radar tracking ability, warning times, RCS so much data etc. They actually showed their Aces when simple Kings/Queens could have sufficed to win the round.
Also, even this time they thought that issuing NOTAMs before the 7th May would confuse PAF, yet PAF tracked each and every one of their aircraft when it got airborne. Next time we have intelligence that they are preparing, rest assured we will have on the ground intel, we know the only trick they have........and prepare for CMs barrage because zero chance in hell or earth that they will risk flying even within 200km of the IB. But then that makes their targeting and navigation of CMs difficult as well over a longer range firing and allows you ample time/warning time.
What Pakistan needs is more quantity of IADS.........and the good part is we need to cover the eastern flanks only.......we already have systems that work, that our people are trained on, that worked in actual combat situation, you simply purchase and integrate more of them.
meanwhile what does IAF has to show for it? Purchase more Rafales? Or more ALCM/SLCMs? Heck, show me one kill they got from the over hyped S-400? Their operators have no idea how to work in a networked environment.....2019 own fratricide is a perfect example of this.
Their M2Ks and Mig 29s and Rafales are no where networked with their IADS........
But this is all weapons and tactics.
Another deterrence was and proven that still is valid today is that of diplomacy. India was pressured by the world to stop. As much as they claim themselves to not be dictated by anyone, no, they are no where near that independent adventurism yet. They had to listen to the world and consider de escalating.
Imagine China went to 4 day war with India........you suppose they will listen to anyone to stop? Nope. But India ain't even a tenth of the super power they claim and make it ought to be.