No but mechanised assaults are. Mounting up on a fast transport and charging the enemy lines is still a viable tactic, what changed is the horse got too vulnera

No but mechanised assaults are. Mounting up on a fast transport and charging the enemy lines is still a viable tactic, what changed is the horse got too vulnerable and the robots aren't cheap or fast enough yet. Humm-Vees, Bradley's and other infantry mobility vehicles with mounted guns for fire support have very much stepped into the tactical role.