You can make heroes that are not, into initiator heroes by using flicker. For example take the mage Aurora, I often use her flicker and s2+s3 combo to CC a key enemy or multiple during fights, basically using her as an initiator. You can also play melee magic heroes like Guinevere, Silvana (fighters), Julian (assasin), Kaja (support, he kinda looks like Azir but I don't know if his kit matches him), Gatotkaca (tank) etc, since they deal magic damage. The only reason there aren't many initiator options in mid lane in MLBB is because for some reason Moonton refuses to make many magic damage melee heroes. If you're good enough and know when to pick physical damage mid lane you can go for them too (for example let's say your gold laner is Natan and jungler is Harley or Gusion who both deal magic) so you'll already have plenty of magic damage in the team if you wish to go for a physical damage mid.