How so? If he choses to do that, that’s his choice. What do you find “annoying” about it? Sounds like veiled jealousy more than anything logical.
Playing multiple alts has always come with increased benefits/perks for the player willing to maintain such alts, nothing new about that. If player A has 10 characters, and player B has only 1 character, then person A will enjoy more benefits/goodies from the game in general; it’s simply a side-effect of playing the game more.
For example, I farmed my Keystone Master this season fairly quickly… because I maintain and play 3 different tanks (Guardian Druid, Prot Pally, Prot Warrior). I think it took me a little over ~2 1/2 weeks of casual M+ runs (mostly using my own key) from when I did my very first +15 to when I got the acheev and mount.
If I played “only” 1 character it probably would have taken longer. But because I put in the work/did all the chores to maintain 3 different tank toons I quickly knocked out most of the dungeons on +15 or higher. Once I was getting repeat/duplicate keys I simply started applying to pugs to finish out the 2-3 missing dungeons I still didn’t have on +15 or higher.
You get out what you put in, and players that maintain alts invest more into the game then a person that “only” plays 1 character.
There is this strange tunnel-vision/fixation on the player that leaves a losing bg, but I never see anyone asking “why?” such a player is leaving in the first place. Until that specific question is addressed, players will continue to bail out of bad/losing bg teams.
This tunnel-vision focus on the “symptom” (people leaving) doesn’t make much sense to me to be honest… shouldn’t the focus be on the “cause” (bad teammates/not doing objectives, low DPS, not killing healers, etc)? Logically you would want to address/fix the cause of a problem, not the symptoms.