Because, you know, it just makes sense to space them out and not overburden the immune system.
It’s all about what argument you are trying to make. In this case, there is zero evidence that lumping vaccines together causes an increase in adverse reactions. To your point, there is a small risk of an adverse reaction to any given vaccine. It’s important to differentiate these points. Parents aren’t withholding their kids from vaccines because of a 1 in 1 million risk of Guillane-Barre Syndrome.