That is true, but you can use the whole FAir assault tactic to make up for that (usage of DB or SB after SH FAir), and that places them in a setup situation once more. Though this is coming from a more unorthodox Marth player, so you can take it with a grain of salt xD With SH FAir specifically, there is enough time to double jump and do another FAir before touching the ground, or just land and grab. There's a few options with the SH method, so I'm willing to defend it has its strong points. Whether FH or SH is all dependent on the person's playstyle and how they make it work for them.