Don't take the term "virtual stacking" too literal.
It is actually a marketing term for the feature that lists all your switchports from a dashboard network on one page, nothing more.
It does open the abilities to config ports over multiple switches in one go by using the correct filters.
The term virtual stacking should NOT be mistaken for flexible stacking which is the term you believe the MS125 should be able to do, but it does not support any kind of real stacking.
Flexible stacking is the term used to modify normal ports to stackports.
The only switch in the Meraki portfolio that supports flexible stacking is the MS425 aggregation switch.