Some times there may be a need to also monitor your employees. Specially now, with the COVID-19 pandemic, when everybody is working from home.
Not only that, but if you decide to show screenshots of your work to your clients using the WP Hourly Tracker, then you may want to monitor the work quality and make sure no screenhsots depicting you or your team working on something other than the project at hand reach your client. For example, maybe you decide to browse Facebook for some time and screenshots of your Facebook account make it in.
That could be a reason for argument. No client would want you to waste time on his payroll and nor would you want your employees to waste your time either.
Therefore, if you have the need for it, you can check and see what everybody is working on in real time, as screenshots get uploaded to your server.