You are correct. An N95 mask is ONLY effective if it the proper size. We actually go through an annual process called "fit testing". If a SEAL cannot be obtained, it is not an effective mask. Someone with a beard will never have a seal. Some very lean faces may not get a seal.
The public buying and using them is a ridiculous waste of resources-both a wasted mask and the $. Patients who really need them are fit-tested for proper protection.
Facts matter!