You are fully fully right. This theory about "the 100 wins dominance" is distorted basically from its roots. The dominance in every aspect of the life is a qualitative indicator. The qualitative indicators are always measured by qualitative methods. That's why you easily found hundreds of huge discrepancies which show nothing else than the absurdness of such theories.I just listed about 20 consensus "all-time seasons" or "dominant" years that would not be considered such under your narrow criteria. Most of the greatest players with the greatest seasons would be left out. That is my "objection".
1920-30s, only Tilden reaches 100, in four years, and this after his peak. Vines does not, Perry does not, Budge does not, nobody does.
1940 and '41 - Bobby Riggs wins 101 both years. These are not generally considered dominant years and Riggs is farther down the list of the greats.
1948 and '50 - Jack Kramer, owing to very long WCS against Riggs and Gonzalez, respectively.
1950 and 1952 - Jaroslav Drobny (104-8 in 1952). Not known as dominant years and Drobny is a special case: stateless and staving off depression, he needed to play tennis 12 months a year.
Gonzalez twice, 1956 and 1957. These are all-time, mega seasons, two of the very few that qualify as such under the 100+/50+ stringency.
Hoad twice. AGAIN YOU MISREPRESENT HOAD TO US. He did not make your 50-plus victory margin in 1959, but was 100-61. Don't be calling this a dominant year, please, Dan. You can read the record as well as anyone.
Speaking of the record - you will see that 1958-62, at least, there is a gap in Rosewall's record between late January and late April or May. He doesn't play any matches. Yes, he stayed home to be with his family. Sure he practiced, and he probably played some exhibitions, but he was there in order to be with his family.
Moving into the Open Era, Connors ('76) and Borg ('78 and '79) only just barely hit 100, but you have to count plain exhibition matches - which you said in the other thread you don't want to do - not just independent tournaments. But only the '79 Borg year is "dominant".
Ivan Lendl played 102 matches in 1985, counting only official and non-sanctioned tournaments, not exhibitions. In 1989 he won 105 counting the independent tourneys, no exhibitions. Earlier in his career, in 1980 and 1982, he won more than 100 official matches, but those are not "dominant years." Although all splendid years, none of these four are all-time mega seasons. For Lendl, those would be '86 and '87.
Finally, as I mentioned before, the 1984 McEnroe season, widely considered one of, if not the, best single season, fails to meet your manliness criterion, as Junior only won 96 matches.
Since Lendl, I don't believe any player has won 100 matches.
So, you are left with recognizing . . . what? Of these 100-victory years, Gonzalez '56 and '57 qualify otherwise as all-time, or dominant years. Laver '62, '67 and '69 can be counted. (IMO the Kramer '48, Trabert '55 and Hoad '56 make the list of greatest single seasons, but at the bottom of that list).
Enjoy your list of "truly dominant" seasons.
In my view one of the best qualitative methods in this matter could be the winning ratio for the year. 80%, 85% or 90% shows the efficiency of the player for the year.
Another method combined or not with the winning ratio should be the balance vs top 10 players. In this way you will avoid any obstructions that a player played many matches vs low competition.
I can go with many figures but just to show the "reasoning" of one Hoad maniac I will show just some win ratios - Hoad in 1959 (the best year) is 63%, Laver in 1969 - 87%, Connors in 1976 - 91%, Lendl in 1986 - 92%, Sampras in 1996 - 85%, Federer in 2006 - 94%, Djokovic in 2015 - 93%, Nadal in 2013 - 91% etc.