Is this the longest running sitcom that has never had a dvd release?

Totally true. Also, don't forget that Nest was a HUGE ratings success for the majority of it's run. It was a Top 10 show for it's first five or so seasons. Mainly because of it's lead-in, and parent show, The Golden Girls. Most people forget that.

Sadly, it will likely never see a DVD release. Despite it's popularity at the time, it's just one of those shows that time has literally forgot. The show has almost become obscure and that doesn't make them money.

"I'm nostalgic for conversations I had yesterday."

Shows predating 2000 are routinely treated like crap by big studios. There are plenty of long-running, highly rated shows that aren't released or given a bare bones release of one season and then abandoned.

Thankfully a few smaller companies have bought the rights to some niche shows and released them. I rather doubt this will happen with Empty Nest though. I can't imagine Disney selling the rights or being interested in something "old" like EN. Pity really because the show was enjoyable.

Some shows are easier to release than others. Shows that incorporated a lot of pop music have to be gone over with a fine tooth comb, and every song with a longer-than-"fair use" clip has to have an application for permission from the original artist, and an arrangement for royalties (plus, lawyers), or else somehow edited out, or rerecorded in some way as a cover. This is the problem with Murphy Brown most likely. It was probably expensive to put together, because every single episode had at least one 60s song in the opening credits, and other songs incorporated, all the Barry Manilow, for one thing. When you need to put that much work into something, the return on the investment is smaller.

Alice was a "small" show. Almost every episode took place on a single set, there was rarely any outside music or other outside sources that needed to be dealt with, and many fewer guest stars to pay royalties too, in particular name guest stars, whose contracts may have specified something more than scale for DVD releases.

Which is another thing. Shows from before the VHS era probably did not include "home materials" (VHS, DVD, digital files) in the royalties contracts on the one-time, and particularly, big name, guest stars, so they may not get anything from DVD releases, and it may be legal, and certainly saves money in contacting every one of them and arranging payment. A lot of the DVD preparation may be arranging royalties, or outright buying, DVD rights to the performances of guest stars. Probably, in the 21st century, studios were more contract savvy, and may have put single DVD fees in contracts, or limited to responsibility of the studio to track down someone who had left the business, but the late 1980s and early 1990s were probably the most difficult time, with ambiguous contract clauses written.