Ignored Offers

I have been buying and selling equipment on this site for many years. I have noticed recently that sellers are ignoring my offers. In one case my offer was more than the item eventually sold for, so clearly it was not a low ball offer. The other item I bid an amount based on prior Audiogon sales. Any one else notice this trend?
Some folks have an overinflated value of their gear coupled with a fragile ego. After the items sits unsold for a while, reality sets and they take what they can get.

 Don't the rules say something like "your offer has been submitted. The seller has x amount of hours to respond"? Meaning if you haven't gotten a reply, assume your offer has been rejected.
While it may be rude (not to respond), it is within the rules.
sometimes people are away from their PC or whatever and don't get the memo on offers. the time limit is a bit of a drag too, 48hrs is pretty short as time frames may go, but I guess the cut off has to be somewhere.
Over a year ago I made a very reasonable offer on a Mc amp and never got a response. The amp is still for sale. I would be nice to at least get a "no thanks" or a counteroffer. 
I asked a question about some speaker wire for sale (4 days ago?) and the seller hasn't answered. Lost sale..
I just had that happen to me on epay.  I made an offer,at least expecting a counter offer,nope,just crickets. The item was listed with buy it now,and make offer. I also don’t feel that my offer was insulting. The real funny thing was earlier that day, I sent the seller a question,and he responded in about an hour.