As recipients of group emails, we have a choice: reply to the sender, or reply to everyone that we can see was listed on the message.
Many of us choose "reply all" expecting that it's appropriate for everyone involved to see your response. But is it necessary? Do all those people need to see simple responses like "thank you for doing this" or "I agree" or "sounds good to me!"
Your organization may have a protocol of ensuring everyone sees all replies. But it's healthy to question why any recipient should get a reply unless there's value in them seeing whatever you're sending.
In short: don't reply-all unless you can demonstrate to each recipient the importance of them seeing your response. Otherwise, try a simple "reply" (if you must reply at all) and see if that ends the cycle. It's easy to add someone as a "CC", it's not always necessary though.
You can't stop someone from adding you, but you can stop yourself from perpetuating it.