IMHO, Inkscape is more of a design tool. Means, people do art with it (logo design, illustrations, etc)
Those who do business diagramming (like building plans or org charts) were never meant to be target audience of Inkscape, as far as I know.
I think Lucidcharts could be much closer alternative to Visio than Inkscape (from online alternatives)
Similarly to Visio, there you have sets of pre-built blocks (shapes) that you could use to compose the diagram.
But the issue is, many people have lots of diagrams already created in Visio that cannot be imported without loss. Lucidcharts can import Visio diagrams, but that import is not purely 1:1
Also, there are lots of 3rd party components for Visio that cannot be found for other applications (like devices, or engineering stuff like pipes etc).