I don't have to worry about where the other person is; I can send WhatsApp messages to my family back in the US, or to friends here in the Netherlands, but it doesn't cost me anything. SMS to local numbers is free, but it's not free to send an SMS to the US
On the other hand, my 6, same purchase day, can barely survive a full day of light use, and requires additional charging throughout the day if I'm calling or texting much
I think the parent is saying less that you don't need valgrind, more that you get it for free. I can take a program I'm writing in Rust and run it through valgrind, or other debugging / profiling tools written and designed for c / c++ because the rust binary ends up with the same debugging symbols that a gcc compiled binary could have