You don't say in your profile what bike you have and it (maybe) makes a difference.
The VERY early K12's had a bleed nipple on the top right hand side of the head. With the bike on the side stand it was 'possible' to fill the bike and bleed the air out using the nipple.
I say 'possible' because although mine had it, when I needed a new radiator I chickened out and paid £50 for the vacuum kit. I already had a compressor!
I guarantee that every BMW dealer uses the vac kit! I can't guarantee that they use it properly.
The problem with not using the vacuum method is you get air pockets in the head which cause hot-spots in the head and this can lead to cracking. Lots of cases on t'internet of DIY folks complaining about it back when it first became common automotive practice. I doubt any of them were BM owners