There’s a big difference between sending a command whenever there is a trigger and sending a command repeatedly from a single trigger.
sending a command whenever there is a trigger is often seen as a feature. For example, if you want to send a “light on” command regardless of whether the current status in SmartThings is on or off, then you can also successfully manage the light even if you are using parallel means of control, such as a hue dimmer switch or Yonomi. In these cases, there’s a polling lag. The light was turned off by some other means and it may take smartthings four or five minutes to realize that. So being able to immediately turn the light on again through a SmartThings mechanism is of value. The only downside is that you might be sending an occasional unnecessary command. But these instances should be rare and have little impact on the network.
On the other hand, repeatedly sending the command of the single trigger can be deadly to your network. First of all, you’ve obviously multiplied the number of messages that your network has to handle, and this in itself Could cause other messages to be missed or delayed. Second, as the OP mentioned, it can really mess up “follow me” use cases where the first device going on or off is supposed to trigger something else.
A few months ago I had a single trigger issuing upwards of 30 repeated commands over several minutes. (I posted some of the screenshots at that time.). It did cause actual problems at my house. For one thing, the light couldn’t be turned off because it kept turning itself back on again. There were other issues as well. Support tried a couple of different things and eventually forced a local smart lighting automation to run in the cloud which seem to fix it at that time, but obviously lost the benefits of local processing.
So the impact really depends on what you’re seeing. Multiple triggers generating one command each shouldn’t be a problem. A single trigger generating multiple commands almost always is, if only in the impact on network efficiency.