I understand your setence, it just never said that the 100 year rule was an actual rule. Never. It's not a plot hole.
*Face palm* okay lets try this one last time
IGA, obviously the former lead (or current that hasn't be released) on Castlevania, stated that there was an actual 100 year rule and that he acknowledges that said rule when asked the question how tied he was to that.
1691: first game in the series (1986)
1698: second game in the series (1988)
1576: though not stated in the manual by the use of math the sequel would confirm the year this happened (1989)
1476: Fourth game in the series (1990)
Super Castlevania 4: remake of the first entry of series stating the legend of the 100 year revival (1991)
1591: sixth entry in the series confirming the hero in The Adventure to be Christopher and that he had not killed Dracula goes and kills Dracula setting up his rebirth to be a 100 years later falling on 1691 the events of CV (1991)
So I think it was a rule being since they released super castlevania 4 as a remake (though in america it was hinted to be a new adventure) explaining why Dracula appeared 100 years prior, stating the legend as said rule. Also all those games came out before 92 before there was NOT a lot of media on video games and press releases that could very state such a rule video game developers didn't get many interviews back then.
But again not the point of this thread nagumo. Read the first post and if it helps you cope pretend there is a rule. Im not explaining this any further. EDIT also I dont know where you got a plothole from? No one suggested it.
"What do you think? Should the 100 year rule be kept and honored since it has been around since the start or do you think it has been holding the series back? Did the creators make a mistake in placing that rule upon the series?" was the question present nothing about plotholes was mentioned.
Now back on topic
100 year rebirth cycle good for the series?
100 year rebirth cycle bad for the series?
Or do you just not care?