Yes, you are right. IMO however, that is just a different way of thinking. In my case, the water pump was leaking coolant, and it is recommended that it get's changed anyway. The radiator hoses are cheap and easy to swap, so they got changed. The push tensioner and idler pulley are very important, so they got changed. IMO, it's always better to be safe than sorry. That "thin rubber belt that could break and destroy my engine" could still break even if it is brand new and your push tensioner or idler pulley fails after its been yanked and replaced...just something to think about.
I'm not trying to convince you to spend more money or do more work, just looking out for you. I would hate to only have done half the job to save money only to have to do it over or cause bigger issues later, that's all. Just food for thought.
Bart