That "toddler finger-painted it with mud" line hits a little too close to home. I had a table once that looked so bad, I told people the stain can must have exploded. My first instinct was to just keep adding more stain, which of course made it into a sticky, dark mess. Thinning that first coat is such a simple fix, but you only learn it after creating a few really ugly pieces.
Wait, you actually told people the stain can exploded? That's hilarious. I'm with @kim734 on the pine being a huge part of the problem, it's like it drinks stain in the weirdest spots. So thinning helped, but did you ever go back and try a conditioner on that table, or was it too far gone by then? I feel like every woodworker has that one piece they just quietly hide in a corner forever.
Thinning the first coat is such a game changer, wish I knew that years ago. My first pine project was a dresser I slathered straight stain onto, and it looked like a toddler finger-painted it with mud. I had these wild dark streaks next to totally bare patches. I was so proud of it too, until my friend asked if it was supposed to be a camouflage pattern. Live and learn, usually the hard way.
When you had those wild dark streaks next to bare patches, was it just the stain thickness or did the pine itself play a part? Pine can be tricky because it absorbs stain unevenly, especially in areas with different grain densities. Did you try any pre-stain conditioners after that, or was thinning enough to fix the problem?