Importantly all of their products are still alive, supported, and even if they're doing superbly do not appear to be on the verge of shutdown.
There are a few problems to Google's way of doing things, having witnessed it from the inside. In no particular order:
1) Google tends to be over-optimistic and under-skeptical when it comes to new products. This is largely driven by organizational dynamics: Google's corporate structure encourages fiefdoms that come up with the Next Big Thing(tm) - everyone involved is encouraged to be wildly over-optimistic about their products, and there is not a countering skepticism from upper management to impose the right amount of discipline re: these wild-eyed claims of TAM, growth, etc. The net effect is that Google launches products that aren't sufficiently baked, with vastly overestimated initial growth. This creates disappointment as the products bounce off the market and do not get anywhere near the (completely fictional) projections.
2) Google's go-to-market strategy tends to be under-baked as well. This is related to point #1 - heavily over-optimistic projections causes Google to accept woefully substandard GTM plans. Stadia launched with an incredibly poor lineup and burned a lot of the initial goodwill and press which stalled any kind of momentum they could've gotten.
3) Google organizationally isn't set up to reward individuals that turn around troubled products. Promotions heavily favor new product, not fixing existing broken product, especially once the product has lost executive favor. This causes team death spirals - failing products experience intense team attrition that further hampers any kind of turnaround plan.
4) Google has comparatively high executive turnover vs. similar companies. This results in rapidly shifting high-level strategy. Products and projects fall in/out of favor so quickly it causes whiplash. Other companies (see: Nvidia, Sony, MS, Apple) seem to be able to identify product areas of strategic importance to the company, executing against it, and having the executive support to continue resourcing these projects even if they initially fail/disappoint (see: Apple Maps, PSVR). Google constitutionally does not have this ability - they talk a lot about multi-year investments in strategic areas but in reality their commitments are fickle.
Though do any of those do the Stadia model of having you "buy" the game specific to them to be able to stream it?
Other systems I'm aware of mostly piggyback on some other platform so your "ownership" extends to local usage also (like how Nvidia's system works with your Steam library), or are just Netflix-esque subscriptions that give you access to the available library as long as you're subscribed (like PlayStation Now, well, whatever it's now called under Plus, and Game Pass streaming).
Neither of those models has the same type of concern over losing your purchases. Google's track record is obviously a factor too, but the business model is as well.
