Also, the factor of upgradability is at issue. A lot of people are replacing receivers due to technological changes such as surround-sound, with changes coming so often that relatively new products become 'obsolete.' FM tuners, as well, have additional digital features now, inluding more than one program on one station; lots of AKer's have bought the new Sony HD tuner. So far, power amps are virtually timeless.
Cuts both ways though, technology has been omitted on new receivers, too; phono preamps are getting rare. (Good tuner sections even rarer.) Nowadays, many vinyl junkies use outboard phono preamps, or keep the nicer vintage receivers.
So it is an advantage to be able to replace only the components you choose to as technology and your possible desire to use it changes. Seperate components give you that flexibility, though it can be more expensive. Even that is not always true, however. It seems there are more receivers than ever that break the one and two thousand dollar price-points, or even higher. When considering those high-dollar receivers, it may well make a lot of sense to go seperates.
For those who want their system(s) to do dual duty as stereo and home theatre, seperate components appear clearly superior; very few, if any, HT receivers seem to be up to the task. A great deal is asked of a 'surround' receiver, maybe too much for them to live up to the 'super-receivers' of the past.
