I live in the northern part of the United States. In the winter the air humidity can be next to nothing. Stand outside for a few hours on a frigid, windy day. You'll get wind burn. So I believe if i can get it, why can't the plants? Not to mention, I've seen it plenty of times on plants. LolReally? smh I have been growing over 30 years and I have seen it many times.
I do the same as you. I keep temps averaged to mid 70s, rh at about 50%. I haven't had a problem since I've gotten dialed in to those specs.VPD = vapour pressure deficit
you can combat high heat or low heat by adjusting your RH for optimum growth based on VPD charts.
personally I don’t worry about VPD.
I keep vegging plants in 50-65% RH and flowering plants in 40-50% RH.