You know, there's a huge difference between 'not seeing' how something can happen (opinion, never experienced it) and having something actually happen (fact, experienced by more than one person). The bottom line is using your drill press to seat press is not the 'right' way to do it. Will it work? Yes, for a few fret jobs. When you've pressed in over 400 frets, it DOES take a toll on the table. It's not user error, it has nothing to do with the 'proper pressure', it's all about using the RIGHT tool for the job.
Sure, a few blocks of wood underneath the table will probaly prevent any problems, but why not just spring for a cheap arbor press? Instead of spending the money on the wood to prop the table, why not invest that into the right tool?
Chris