The problem seems to be associated with the Vulcan's telepathic abilities.
In TOS "All Our Yesterdays" Spock is influenced by the savage emotional nature of Vulcans from 5,000 years passed.
MCCOY: Are you trying to kill me, Spock? Is that what you really want? Think. What are you feeling? Rage? Jealousy? Have you ever had those feelings before?
SPOCK: This is impossible. Impossible. I am a Vulcan.
MCCOY: The Vulcan you knew won't exist for another five thousand years. Think, man. What's happening on your planet right now, this very moment?
SPOCK: My ancestors are barbarians. Warlike barbarians.
MCCOY: Who nearly killed themselves off with their own passions. Spock, you're reverting into your ancestors five thousand years before you were born!
So the emotions of those Vulcans were telepathically enhanced, amplified to the point where they could influence Spock thousands of light-years away. The telepathy created an emotional echo chamber.
This fear was a definite possibility in the case of Sarek suffering from Bendii Syndrome in TNG: "Sarek"
CRUSHER: There's a very rare condition that sometimes affects Vulcans over the age of two hundred. Bendii Syndrome. Its early symptoms include sudden bursts of emotion, mostly irrational anger. Eventually, all emotional control is lost.
PICARD: I can imagine nothing that would be more offensive to a Vulcan. Their emotional detachment is the very core of their being. How would this affect others on board the ship?
TROI: Vulcans possess telepathic ability. Sarek may unintentionally be projecting intense emotions onto other people, at random.
So the danger wasn't just to Sarek. His telepathic abilities would influence those around him. They would feel his emotions.
On the other hand, the Romulans seem to have abandoned their telepathic abilities. They are a genetic offshoot of Vulcans, but they do not appear to have any telepathic abilities. If they do, those abilities are not as enhanced, refined, focused, or controlled as in Vulcans.
So the Vulcans appear to have used logic to suppress their emotions while maintaining their telepathic echo chamber. The Romulans, on the other hand, seem to have gotten rid of the echo chamber and kept their emotions.