Maybe this is a hot take. However, a lot of the Chromebooks that were deployed by schools during covid are build like tanks while being super lightweight and having great battery life. Meanwhile the old thinkpads are 10 years old and are probably starting to wear down. Many Chromebooks support coreboot these days so theoretically they have the potential to be more private and secure. Some of them are also arm which means that they are more efficient from an architecture perspective.
Edit:
I like how incredibly controversial this is. I have successfully split the votes
My experience differs. I used a Chromebook that had a Celeron and it worked pretty well, not much worse than my Ryzen 5 4000x laptop on Windows or Linux.
Not sure if Linux would run better or worse than ChromeOS on that Chromebook.