I LOVE Eberron as a setting and have run a pair of campaigns there before... but I have always known of and have had to try and reconcile the one fatal flaw of the setting:
Eberron is meant to be a wide setting when it comes to magic-- magic is everywhere and everyone uses it in their everyday lives... but it is not deep. There are exceedingly few high-level magic users in the setting, which is why magic items and magewrights/artificers are so prolific-- they are creating objects that allow for the more powerful magics to be wielded by many more people, because there just aren't enough actual magic-users able to wield that powerful magic themselves...
...except for the three to six members of the D&D party playing the game that are the stars of the show.
This has always been my stumbling block with the setting. How is it that we are supposed to make groups like the Dragonmarked Houses (for example) meaningful to the players and their characters-- groups that the party should want to deal with and interact with-- when those PCs will out-level them all and end up more powerful than every single other NPC person, group, or organization that they might ever come into contact with? It's hard to make the party want to interact with members of House Jorasco for healing when the Cleric in the party has more spell slots for more healing and more varied and powerful recovery options then any dragonmarked member they would ever interact with in a casual manner from the House. The issue of standard D&D leveling and character advancement completely runs counter to how characters within the world of Eberron are meant to be. At least in my opinion.
I honestly think Eberron as a setting is one that really should be run as an E6 game-- a game where no character advances past Level 6-- so that more powerful magics always remain out of reach of the party and then would require them to have to interact with the few and far between NPCs that have those powerful magics they need, or the magic items they can acquire. If teleportation circles remain only in the hands of dragonmarked members of House Orien and not at the party's beck and call just because we as a table were playing Eberron with standard D&D advancement and the PCs are now all 9th level... it would do a lot better to maintain the aesthetics of the setting.
I think this is a common misconception of Ebberon's world building. There is high level magic, about as much as Krynn, Mystara, or most of Oerth. The two things is that high powered magic is not openly part of society. Magewrights, dragonmarks and dragonshards free high level wizards and clerics from the mundanity of running temples and building lightning rails, so that they can be threats and important allies, not merchants. Or on the other side, not so many of them that the PCs are never not needed. There is no "let Drizzt or Elminster handle it" scenario, you aren't playing the Defenders waiting for the Avengers to show up, but it also doesn't mean Dr Strange and Dormammu aren't there behind the scenes either.
Limiting Eberron to only low level magic/play (e6) robs Eberron of the biggest threats: Daelkyr, Lords of Dust, the Quori, the giants of Xen'drik, the Lord of Blades, Lady Vol, etc. They exist and threaten Eberron in a variety of ways. You need someone to handle those threats and if Eberron doesn't have a Circle of the Eight, it's gotta be your PCs.
I think the other issue is that in D&D, magic item creation was primarily the realm of high level wizards. Eberron didn't want to make every member of house Cannith a 9th level wizard, so they created the cheats needed to allow low level non-wizards to make magic that replicated modern technology. That doesn't mean 9th level wizards don't exist, just you don't need a lot of them to justify the absurd level of everbright lanterns in Sharn.
So yeah, 9th level wizards still exist in Eberron as NPCs, it's just there aren't thousands of them and they aren't spending their days making eternal wands.
