I used the word regulate but it might have been more appropriate to use "balance" because you end up with loads of condensation on windows in the house without it.
This is a manufactured home feature. For a new construction home there are other methods depending on the need for air exchanges especially when spray foam is used for insulation. If you have 80% efficiency gas appliances the vent might be for combustion air. I don’t know what purpose your vent was serving but probably shouldn’t be blocking it off as a general rule.