I think it's a little disingenuous to say Holtz has been given a lot of opportunity. He played 9 games in 21-22 and averaged 10 minutes per game at even strength and 2 minutes on the powerplay. Last year he only played 19 games, averaged 8 minutes a game even strength and 1:39 on the powerplay. His most common 5v5 line mates over his career by a wide margin were Boqvist and Sharangovich, neither of which are particularly gifted playmakers. Comparatively he's only played for about 14 minutes with Hughes and Bratt, which is a line that would make a lot of sense for him. He played more minutes with Zacha than he has with Hischier, and spent almost as much time with McLeod (40 minutes) as he did with either of them.
Here are the gaps in days between games he played this year as well as time on ice:
(14:36) 2 days (9:20) 3 days (5:55) 8 days (12:29) 34 days (10:02) 3 days (15:07) 2 days (7:03) 3 days (11:59) 3 days (9:46) 3 days (4:14) 3 days (15:08) 2 days (9:51) 3 days (10:26) 3 days (7:34) 7 days (5:47) 5 days (13:21) 1 day (13:34) 2 days (8:55) 35 days (9:52).
It just wasn't consistent enough playing time for any meaningful progression to occur. He was given a little bit of runway to start the season but by his third game he was only given 6 minutes, then played one game in 42 days, got essentially a 14 game stretch after that but that was the period of the year where the lines were constantly in a blender and his ice time was all over the place. He was played like a 14th forward and got 14th forward results. I'm not saying he deserved more, but his performance last year doesn't push the needle in the wrong direction either.
Meanwhile, he has 32 goals, 62 points in 66 AHL games over those same seasons and 1G, 7A in 11 playoff games. I can buy an argument that Gritsyuk's performance in the KHL is more impressive, but it's not like there's no track record as a pro here. I want to see him actually play regularly before I write him off.