Can SSRS used to Update or Modify data tables?
If Madeira Data shows you how to do it, then I think it's safe to say:
It's possible.
It can be made to work, as evidenced by this paragraph from them:
It’s especially good when your organization doesn’t have skilled programmers that can create a pretty-looking graphical user interface (GUI). Or when there are budget and / or time restrictions.
Deciding if this kind of setup will work for you is entirely your decision.
I've used SSRS for a subset of this kind of activity.
It's not great for using as a full-on data input program for obvious reason, but there's no particular problem with running insert/update/delete statements inside datasets.
What I've tended to use it for is more "clicky" kinds of updates. Where clicking on a hyperlink within a report causes something to happen - be it insert something in to the database, update a value somewhere, etc. And the activity that happens is controlled by the hyperlink passing in the various parameters to control that.
I've tended to use a report where the hyperlink runs a new instance of the same report, but controls what gets updated by passing in new parameters. Mainly so that all the code is in a single report.
I've made a quick demo report to demonstrate the technique in action, if that'll help? Available at: https://github.com/JerBoon/updating_with_SSRS
You can do quite sophisticated stuff within the confines of this technique, but it's definitely not a data entry portal for entering entire rows of data. I'd be interested to hear if anyone's really used it for that in earnest.