The current meta we play in is all about getting the single most kills as quickly as possible with the least amount of effort - Scout Rifles do not fit into this at all, as they require effort and a good aim. Thorn and The Last Word can 2-hit headshot and 4-hit body shot, while a Scout Rifle can only do a 3-hit headshot at best, often 4, not taking into account how detrimental missing any one bullet is. I have seen many times people commenting on the fact that Snipers cannot suffer from damage drop-off over range in Crucible, yet I see no mention of the numerous Scout Rifles that have more range than some Snipers. As for Trials, it is a mode that fluctuates greatly and frequently. Some maps, like the current Widow's Court, are advantageous to a Scout Rifle user in most situations. Others, such as Thieves' Den, are horrendously tight and twisty, catering more to Shotgun range encounters.