Not exactly. Office Online provides a real good co-authoring experience - with quite fast updates.
What Office Online lacks, is the full support to features desktop applications provide. Especially on Excel. But this depends a lot of what kind Excel spreadsheet you have.

Usually the best practice is to use latest versions of Office 365 client apps to make sure co-authoring also works the best way - and be used with Online versions also.
www.000webhost.com