Take the "Size" parameter. You can control it via the pot on Clouds. And you can also modulate it via patching something like an LFO into corresponding input on Clouds. But what you will also want to do is control the amount of modulation you send to that parameter, for which purpose you'll need to patch your modulation source (your LFO, say) into an attenuverter and then patch the output to the size input on Clouds. Now can can control the amount of modulation you send to Clouds using the attenuverter. On other units, the intermediate patching isn't necessary: the six little pots on Rings, e.g., allow you to attenuate the amount of modulation sent to the various parameters.
True, you can do this via the MIA or channels 2 or 3 of Maths, but utility modules, whilst boring, will really help you to make the most of the more exciting modules like Clouds. And since Disting now supports Sample playback ala Radio Music, I'd personally get something like ATATAT instead.