No, I do not believe that an in-depth background check is necessary for every applicant for every job at every company. Of course, this depends to some degree on what you mean by an in-depth background check. I do not think that it is necessary to run criminal record checks or anything like that on most employees in most situations.
To be sure, it is important to run such checks on many employees. For example, it makes a lot of sense to have background checks for teachers and for people who work in day care centers. It also makes a lot of sense to run such a check on someone who is going to have a lot of access to money in unsupervised situations. I would not want to hire an accountant, for example, without doing a check.
On the other hand, there are many jobs in many situations where such checks are hardly necessary. A person who is cooking hamburgers at McDonald’s (which I have done) is not in a position of enough responsibility for it to matter. The same might be true of someone working on an assembly line.
If you do background checks on every applicant for every position, you are likely to be spending money unnecessarily.