To be fair I never understood the problem with AMM spam against beam ships. I really never find myself in a situation this is a problem. As my fleets usually are designed to fight either box launched or reduced launcher attacks I tend to have enough PD to deal with AMM if I'm force into a close range situation.
Aside from that I always must prioritise AMM ship with ASM first as they are usually key to defend against mass missile attacks. So when it is time for close range attack most of the AMM ships should already have been disabled along with most beam ships.
If you have a beam only fleet than PD to deal with AMM should not really be much of a problem to begin with unless you charge a fleet that is much larger than yours. If you also is faster then them you should still be able to use your shields to tank AMM spam by taking some hits and retreat out of their range... is there much reason to charge them until they just spent all their AMM against your shields.
AMM should in most situation be a none issue.
In point of fact my current game, for my faction, is beam only. No missiles to be found. Current fleet consists of 45kt carriers loaded with 400t rail fighters and 12kt “destroyers” that are armed with particle beams. As it’s a 10% research game I don’t have a lot of excess RPs to splash about, and I roleplay a parliamentary system that, amongst other things, severely limits the tonnage of my military assets (although I have a VERY robust commercial side).
The practical effect is that I am almost always fighting a superior sized force tonnage wise, and have virtually no RP to splash on gauss technology. Rail fighters can take out enough incoming ordnance to protect me from ASM’s, but AMMs can get through.
Since I don’t allow myself to respond to the glaringly obvious 5 second forced increment screaming “incoming AMM spam” until I actually see the missiles on scopes, and the AI is rarely stupid enough to launch at maximum range, I can’t bounce in and out of range to recharge shields. Since I have no missiles I can’t take those vessels out at range...I need to weather the storm instead. Hence armor over shields, because I need a win button for multiple potential engagements, not a win more button for beam engagements where I can crush the opfor with or without.
I “could” twiddle about for a couple centuries to get all the myriad techs, but since I have “spoilers” enabled and they couldn’t give a rats behind about tech speed settings...no dallying about.