Darius blows against competent opponents. Your own fault if you get hit by his slow telegraphed Q. He has zero mobility and low range, and zero defensive tools. He has to actually land his skill shot to heal (unlike say, adcs who can't miss when lifestealing, or champs like aatrox with so much sustain against champs AND minions in ALL of his damage sources). In a fight between equal players, champs like jax and aatrox will destroy darius. Can't say how many times I've actually managed to land all my abilities against an aatrox when even or better in items, why juking half his kit, and I still don't even manage to bring him below 50% hp before he wipes me.
Also your claim about darius pressing and his hp being full is complete and utter horseshit you moron. He heals based on % MISSSING HP. Meaning he can NEVER heal up 100% on Q alone, because the heal is only decent when hitting one target, pretty good when hitting 2 or 3, but capped at three. Meaning he will NEVER heal even CLOSE to his full hp bar even with spirit visage. If he already has 90% hp, then the most he will heal is around 4.5-5.% hp IF HE MANAGES TO LAND Q on three morons at once.
Considering how slow, telegraphed, and short ranged he is, against so much mobility, range, insane damage, and cc, and his own inability to dodge cc, he will rarely get a three man Q in a game unless outrageously ahead or in an extremely favorable comp matchup. He will normally land a three man Q like 1-3 times in a game. And then still proceed to blow up instantly afterword.
Plus the irony of you bullshit is not lost on me. Sylas himself has insane heal, a shield, solid mobility, longer ranged abilities than darius or renekton, the ability to steal ultimates, pretty dang high damage, and solid cc. So quit you're moaning about darius. You literally play a champ just as strong, if not stronger than darius overall. Darius doesn't even break 50% winrate. Fricken whiners.