WotC has waffled hard on what was required. 3e began with the same "only need the PHB" ethos and quickly grew to cross referencing other books. (PHB 2 for example, had several items that were for classes in the Complete line of books). 5e started with the "Only need the Basic Rulebook" which was a free PDF, for their first two APs.
Remember These? That quickly fell away as the game expanded and it was clear they needed the full Trinity minimum. And that has kept creeping up. Ravnica referenced all the subclasses in Xanathar's for guild placement. Eberron referenced every cleric domain in print for the deity section. This is just first time that a subclass has been added to the artificer without the class being reprinted soup to nuts (when the artificer moved from Rising to Tasha's, they added the fourth armorer subclass).
Now would I like the artificer in the SRD? Yes. But I don't think it's going to happen. The 5.2 Basic Rules don't even contain everything that the 5.1 did (like the noble and folk hero/farmer background). Hell, it doesn't have the aasimar and they were in the 3e SRD since 2000! And since the artificer is the main draw to Forge of the Artificer (a book I feel they made intentionally at the lowest price point they could) I don't expect they will give it away for free. In fact, I'm pretty sure they are giving it to D&D Beyond users because of the character generator and not wanting to fend off complaints that people paid for seven subclasses but only got six. It's not exactly fair, but its kinda the limitation of paper media.
(It's also worth noting the class will be somewhat incomplete, as it won't have access to the infusion-made-magic items or the create hommoculi spell without FTA. And the only sub it will have is reanimator.)