On the flip side, using caps in your title tags also doesn't have any negative impact. No one really likes being shouted at but using capital letters in your title tags won't lead to a Google penalty.
Gary Illyes from Google said this on Twitter using caps, of course:
@mishasilin NO— Gary Illyes ᕕ( ᐛ )ᕗ (@methode) April 14, 2017
So there you have it, shout as much as you like!
Forum discussion at Twitter.