A lot of these perl one liners are from the old days, from unix admins that had versions of sed (or find, etc) that didn't have fancy features like -i (inplace edit).
Also in the old days tools like sed and awk had more arbitrary limitations. E.g., line length was limited to something (reasonable) like 8192 bytes but input data I was processing was not reasonable.
A lot of these perl one liners are from the old days, from unix admins that had versions of sed (or find, etc) that didn't have fancy features like -i (inplace edit).