To put it this way: The best places I've worked at also had good interview rounds, while some of my least enjoyable employers had less enjoyable interview rounds. The absolute worst interviews have been at places I didn't get an offer, or I didn't pursue afterwards.
If the person interviewing me is rude, glued to their phone, uninterested, and in general indifferent to what happens - I'm going to assume that's a reflection of how the company culture is. I can also understand that not all people tasked with interviews will bring their A game every time, and that there may be external factors at play - but those places usually show a pattern.
I've yet to interview at a place where the interview was terrible all around, and then find out that the company is gold.
I wished I had known this earlier in my life.
I once interviewed at a healthcare startup ran by the brother of someone very closely related to the current occupant of the White House. This was 3 weeks after I graduated college.
I went through the first round, no problem. 2nd round, it was Halloween, and a nurse dressed up as a cow (spotted makeup and all) comes into the room and asks me to role play a situation where I have to deny life-saving insurance claims to a cancer patient who's been given a life threatening diagnosis.
Halfway through the exercise I asked the interviewer - "so, this is an insurance company, and the insured has been paying premiums for a while, probably 10s of thousands of dollars, and they have what is otherwise effectively a terminal diagnosis...and you're asking me to deny this person their only chance at survival?". I was given the response of "that's how insurance works"
Sad.