I don’t know if i’m fully there with this advice. Some of it sounds like the writer wants you to be more monotone than you feel. To control the way you express your reactions.
Expressing your own emotional reactions to/in front of a child is surely important in their development.
That said, the writer’s key point about accidentally switching a child’s motivations for learning things through the parent’s actions is well put.
eeeh a lot of these articles read like the professional in question had parents who used A Specific Tone when saying certain phrases that wildly distorted the meaning and fucked up their self esteem.
Which like, yeah, it happens, but doesn’t mean it’s universal. And you’re doing more damage by dancing around the phrasing when what you should be doing is digging into tone and intent.