It wants to do full rebuilds of all indexes. And these processes are logged. Low fragmentation? No problem - full rebuild. Large table? No problem - full rebuild. Low on disk space on your server, and you really do not want your log file to grow. Problem!
Years ago, in my days as a DBA, I created a process to review all the indexes for fragmentation, and then do targeted updates. But, that was years ago when we all carried flip-phones. Fortunately, Ola Hallengren has released a complete set of index optimization tools that work with current versions of SQL Server.
You can find them here: https://ola.hallengren.com/
And, if you need some additional suggestions on the best way to adjust all the optional parameters, start with the post at Brent Ozar: Tweaking the Defaults for Ola Hallengren’s Maintenance Scripts.
And did I consider digging out my old index optimization scripts? After looking over the work Ola Hallengren did - not a chance.