The primary strength of online drawing tools is the "plug-and-play" factor. There is no installation, no license keys, and no bloatware. You open a tab, and you are drawing within seconds. Tools like Kleki excel here by mimicking the familiar interface of industry standards (layers on the right, tools on the left), reducing the learning curve to near zero.
Here is a breakdown of the current state of online drawing tools.
Master the Flow: The Ultimate Guide to Freestyle Drawing Online