On top of that critical late game chokes really want some gate raiding support on the neighboring planets. Late game wave + hunter + warden + praetorian guard (I've seen this happen a few times and it isn't pretty) = 400+ threat fleet wrecking ball. The AI gets really antsy when you had to neuter the adjacent defense worlds to the AI core world because you're having to quickly destroy one or two guard posts and then gtfo because 5+ Dire Tethuida posts with a few dire shredder posts with a couple dire gravity posts for good measure just makes for a massive pain in the rear for a strikecraft heavy comp.
Basically on higher difficulties you don't have an option. You *have* to neuter immediately adjacent planets to critical locations before the AI can spice it up with an extra few turret nests and several hundred threat of ships.