VBSS is a naval fighting unit so maybe yeah they need guns? that too close quarter battle compatible ones due to the kind of things they do,
...
but advanced... Sterling is not advanced; but it's not even basic, 'specially in this age and time,
it's just flintstones version=primitive tier submachine gun that we're still using because OFB got license+ToT of that and we made shit tones of these and still we've plenty of them lying around...so army-armed forces just kept using it (otoh kept bitching for a replacement ;5.56mm carbine; but each and every time those things just went upside down and didn't happen due to one reason or other, like all major small arms
pogroms programs here
)
even RR and those units in the army adopted to Micro Uzi, B&T MP-9 and such things in place of Sterlings for CQB,CI etc ops...dunno when Navy will wake up...
[waiting for some smart ass mentioning how in da vietnam war USMC and so used MP-40,M3 'Grease Gun', Sten, Sterling, french MAT-38,MAS-49 etc all open-bolt submachine guns and yada yada,
just STFU retard, this is not your grandpa's era anymore, upgrade morons upgrade!]
Even Sten that came before Sterling was very infamous for accidental discharges due to the open bolt nature = working parts are locked rearward by trigger group-constantly under spring tension, and trigger just lowers stopper (technical term = sear) when pulled so if you drop it hard or some other god-knows-what reason end up depressing that sear thing some way, it'll release the bolt and go bang bang...and that's exactly how many people got injured...lost their lives...
just look at this gif and you'll get the idea what i'm trying to say (it's on Sten but Sterling is similar)
(gif credit - historical firearms)
just search "Sterling" and you'll see some recent posts on this very forum about such case(s) here, and yet...nothing...