Very often, high production situations require blasting and painting anyway.
A hi-volume snow-plow manufacturer near us does their welding with GMAW and then blast and powder-coat their products.
On the medium volume side, structural fabricators may blast their pieces for multiple coat paint systems. Or when shop primer is all that is needed and blasting is not required, chipping slag and power wire brushing might be all that is done. (Shop primers are not considered a high quality coating and are not intended for long term protection anyway.)
Some shops find that whip-blasting is faster power wire brushing, but it is important to note that blasting usually does not thoroughly remove weld slag.
For higher volume, manual weld slagging, you are right in that needle scalers are fairly fast.
Chet