How many of the shows on that list got TWENTY SEASONS like GUNSMOKE?
Or ELEVEN SEASONS like M*A*S*H?
(which also closed out as the all time most watched show - 105 million viewers)
LASSIE had 19 seasons as well.
If one is going to quantify TV shows in an "All Time Great" category, one needs to start at the beginning way back in the 1950's and go from there.
Otherwise it's just a preferential list pulled out of somebodies ass.
(also, that site doesn't let one use Adblock, so it's on my chit list right from the start since I don't know it well enough to trust it)
Addendum:
According to this list...
https://en.wikipedia.org/wiki/List_of_longest-running_scripted_U.S._primetime_television_series
Fourteen of the top 20 longest running shows on TV all began before the year 2000.
That's a statistic that one can assume without any doubt includes the most popular shows ever.
(unfortunately, not one of the Star Trek series is included)