I think it depends on the method to an extent. The presence of livebaits and lures can be masked by heavy rain imho as I think the surface noise/vibration overloads their senses and makes noticing moving prey more difficult, compounded further by poor water visibility. Deadbaits still smell though so may be a better option in heavy rain?
Thinking about it, I can't ever remember catching a good pike in heavy rain, but then again I don't usually bother going if it's raining too much. Catch 22?
Give me a big wind any day.
Not convinced about high pressure being particularly poor tbh. I lure fish for pike all year and catch plenty in the summer months in generally high pressure. I know a lot of people don't like it for pike but it doesn't bother me unless it's married to a still, hot, sunny day... and even then you can catch pike, especially on lures where you can trigger a reaction strike. I'd expect it to be the same with livebaits during the summer but I'd never, ever use baits in summer.
You can catch pike from the lowest to the highest pressures, and everything in between, so it's only occasionally a total waste of time being out fishing... one thing is for sure, you can't catch them if you haven't got a bait in the water.