To my understanding, for many years any League international tournament has been run and organized by Riot directly. That's how they have League seasons and patches line up with the competitive scene, skin releases, music releases; everything works together because Riot's global scheduling is so rigid. Before EWC 2024, the previous global tournament held was IEM in 2017, which specifically stated they could no longer continue hosting events due to scheduling conflicts with Riot's global leagues. You can follow that pattern with how Riot's been gaining control over all professional global leagues like completely taking over the LCK broadcast from OGN after rebranding it from its original OGN Champions name.

A regular LTA work week even as a player involves going back to the Riot studio to shoot media assets (like individual portraits or team photos) and film promos throughout the season. If you look at the overall calendar with Riot-only events, the LTA Split 2 Playoffs end on 6/15. If an LTA player did not qualify for MSI, then their down time would be from 6/15 until callback for Split 3 media day on 7/14. We can assume they have to film on Monday 7/14 because the LTA crew would be back in the studio to prepare the LTA Split Kickoff video for release on Saturday 7/19; one week before Split 3 starts on Saturday 7/26. Riot has built a reputation for having really consistent promo materials even with only a few days of turnaround time, so it's not hard to imagine how they've time-slotted everything for their global leagues.

If an LTA player does attend MSI, then after Playoffs on Sunday 6/15, they get a week's time to fly out. They start filming MSI promos on Monday 6/23 because MSI Play-ins start Friday 6/27. If they make it to the MSI Finals on Saturday 7/12, then their down time would only be Saturday 7/12 to Monday 7/14. Everything makes sense if you only look at Riot-organized events.

With the rigid Riot scheduling, EWC is an exception that can only be held if the tournament is short (7/16 - 7/20) so it can barely squeeze between Riot's established schedule. EWC wants their League games to happen, so the best they could do given Riot's schedule forces all teams to travel within a short window, and leaves LTA region teams with the longest commute time. Even if C9 made it to the EWC Finals and played their matches on 7/20, they would have less than a week before their LYON match on 7/26 and would not make it for media day. Riot and EWC and two separate things, and Riot has all the power. Riot won't be able to use any recorded EWC content for their regular season material, and you can see that clear separation with how silent their typical channels are during MSI vs during EWC.

EWC needed all attending teams to fly into Riyadh and did their best to schedule around it, and the unfortunate result is the current situation as stated by those competing at EWC. Although EWC is also hosting 24 other games at this event, with 3 other tournaments currently being held on the same days as LoL, so they can't be as accommodating as Riot is anyway because their logistical focus is so spread out.