He scored 10 goals, none of which were penalties, missed 13 big chances and had a conversion rate of 26.3%. I'd say that is a decent goal threat whichever way you look at it, particularly for a 20 year old inexperienced striker having his debut season in the Premier League playing for one of the biggest clubs in the world against some of the best defenders in the world. Even what we consider mediocre defenders in the league are extremely challenging to face for a striker of his age, because it is a tremendously physical and fast-paced league where you simply don't have the time to react as one would in leagues like Serie A or Bundesliga. He also scored 5 goals in his debut Champions League, which is also fairly decent.
Anyway, we like the players we like, and it comes down to preference. It is clear you prefer a striker with a more refined first touch and a classy one, rather than the physical, heavy brute-looking clumsy kind that is more fitting for someone like Højlund, and that is fine, but to suggest it is not impressive to do what he did is a bit strange, in my opinion.
Martial was more impressive because he was extremely exciting to watch, and the fact that he did this from the left at the age of 19, and combined with the fact that he had absolutely elite talent. With a great mentality and attitude, and luck when it comes to injuries, he could have been one of the best players in the world.
In general, I don't really think anyone disagrees with your point. Højlund isn't good enough, and he has been awful this season. That doesn't mean people have to insult him or suggest that he is the worst striker we have ever had, or that he is a League 2 striker. He clearly has talent, and some of the most recognised scouts in the world acknowledge that, whether we like that or not. He was doing well for Atalanta and was in the top-end percentiles for goals and expected goals per 90 at the time. I think he made a mistake coming to us, and he would have done far better staying at Atalanta to continue his development in a weaker league without the colossal pressure on his shoulders, but can we blame him for joining his favourite club growing up when the opportunity presented itself? Young players are inconsistent, and there will be ups and downs with him, as there will be with most young players. Isak scored 17 goals for Sociedad one season, and then 4 open play goals the following season. That does not mean he was shit or that he would never be a good striker, as we can see now.