Subform Parameters

[Das Goravani]

The docs have this paragraph:

You can send parameters to the subform’s $construct() method by including a comma-separated list of parameter values in the $parameters property when you create the subform field. The $parameters property can only be assigned in the remote form editor, and it has no effect at runtime. If you attempt to set it at runtime in your code, the error "$parameters cannot be assigned at runtime" will be displayed on the client.

Why would they have parameters that have no effect at runtime?

When then are they good for?

Does this mean something else? 

Will I find that the parameters property works at runtime?