It’s easier to target a specific area or person, regardless of the provider and legalities can be ignored. Its best feature is that it’s portable and likely hard to detect because it doesn’t need to be turned on all the time. The second best feature is that training people to use it is probably really easy.
If backdoors exist or not, the setup and use would be significantly more complex. More people would be aware, there is more risk in getting caught, there will always be system logs somewhere, etc.