Official response from JLee:
"Its because we really didnt want the Maxim HMG to be an attack-move and suppress everything unit. Because of its fast setup and teardown, being able to lockdown a bigger area felt like it could be a little scary. I'm not saying excluding the Maxim was the right decision but we wanted to leave the possibility of that issue out for now and see how this improves all other HMG teams and come back to seeing if the Maxim also could use this. "
I am the one who asked in official forum's patch feedback thread about why Maxim receives no near suppression buff. In fact I have keep "protesting" since the last alpha. This official answer has made me once more losing hope.
I would like to say, whatever you say Maxim HMGs can fast reposition, more squad member...etc, A HMG is totally useless as a crowd-control tool while it could even didn't suppress both of the two squads walking together. But I dun think they will even give attention on this, as they even not going to give maxim a half near suppression radius buff to test...
And for those who says that maxim should not have such buff becoz of more suqad men and short setup time, or says that Maxim acts like a LMG team, let me ask you one question: will you willing to have a MG-42 increase squad size to six men, and a faster setup time, but you can only have it exactly same status like the Maxim? (Which means no more than one squad could be suppressed by same time, and your acr of fire is also reduced.)
TL;DR : why dun just give a less near suppression radius(like 6 instead of 13) to the maxim?