Is other company spying on other company via job interview?

I recently went to a job interview.After asking about my skills & experience,the interviewer asked me about the processes in my old company.The interviewer dilligently wrote down all I said at the back of the interview paper.Do i have the right to refuse to answer in the future?

Imagine the hundreds of people who turned up for this interview,the people who work in the same industry,the people who spoke about the things happening in their current company or old company.Will the interviewer implement these processes in their current company.

Ended up the company getting better,while many wasted their time,effort,money to appear on the interview day itself.

Since then I have not heard from this company.