I've gotten a couple customized recruiting emails recently where they actually looked up my background and thoughtfully explained they the position would be a g

I've gotten a couple customized recruiting emails recently where they actually looked up my background and thoughtfully explained they the position would be a great fit. I was impressed, and I figured the least I could do is write back and ask for more information. Well, it's been two weeks and I haven't heard back from either person! It's almost like the twilight-light zone. Why spend all that time researching and writing to someone only to never respond again?