I believe the "no dirt rule" is just a carry over from some other tag game and should not even be a part of this game. As long as the theme of the tag is not the most inaccessible mud hole ever, it can still work. If the theme is a gas station, it doesn't matter if they are all on dirt roads in your area, but I only have a road bike. And If I chose a deserted highway for a tag, any major road in your area should work even if it's not paved. Imagine the possibilities, not the potential shortcomings.
This game will only be boring if the players let it be boring.