Nope, the Philips and some RCAs (notably the DRD435) never did.
This is how you perform a factory reset on the DSX5500c:
1. Hold down the 'menu', 'up' & 'down' buttons simultaneously for 5 seconds.
2. After the box finishes 'refreshing' (may take 10+ seconds or so) you will see a screen titled "Auto Diagnostic" with a bunch of other selections.
3. Using the remote, hit 'sat', '5', '5', '5' then 'OK'.
4. You won't see anything on the screen- if the code takes you will see something to the effect of 'Press [some button] for Rom? [something like that, my notes are vague] erasing"
5. Press the button it tells you to.
6. The screen will reset back to the original menu with the selections. There should be an 'OK' next to the 4th or 5th selection now.
7. Press the 'menu' button and the box will restart with all the factory settings "reset".
8. Go through the guided setup wizards like normal {English or Spanish, Dish Type etc.}.
BTW, if I recall correctly, the DRD435 does have a 'restart' feature as well. It was either 'info' and 'left', or the 'up' and 'down' buttons pressed at the same time.
There's only a few boxes that do not have a diagnostic screen/advanced setup screen: any model of DirecTivo, and the H20-100.
Hope that helps.