One of the stupidest aspects of modern politics is the phenomenon of the MnDoAP. I have no idea whether topics have already been made on this as I haven't been around in literally years (so forgive me if I'm repeating an existing thread) but I come from a time when this wasn't a thing. An MDoAP was an MDoAP, and alliances turned into pariahs when they failed to honour them (and were respected forever when they did.) A non-chaining defence clause basically renders MDoAPs a fancier sounding ODOAP. It's a treaty for politicians, not friends. You're all complaining that politics is stagnating. Why not cut the bs and only sign a treaty when you actually mean it?
I know you all know this, but the reason a chaining clause is important is that an alliance is unlikely to be directly attacked, but drawn into a conflict as a result of treaties. That is because alliances in the politics of this world are rarely important in their own right, but are part of groups of alliances (sometimes blocs, sometimes less formal than that) which have political interests *as groups*. So in order for a mutual defence clause to be meaningful, it needs to be chaining. Otherwise, your ally can find themselves vastly outnumbered and getting rolled while you don't lift a finger, because it wasn't a "direct attack." If you trust someone enough, promising to come into a chaining war with them isn't a problem, because they can always excuse you. And if not, why the heck bother with the whole "mutual defence" farce in the first place?
Basically, grow a pair.