Why put measure units in the own constructor when currencies share the NumberFormat constructor?

[sffc]

Measure units (meters, joules, seconds) and currencies are two ways to specify the thing that a number is quantifying. Why should one have its own constructor while the other is part of NumberFormat?

See tc39/ecma402#215 for my proposal, adding measure units as an option to NumberFormat instead of having its own class under Intl.