Eagle is far from an industry standard. In fact I don't remember hearing about a single company who uses it. Perhaps some small companies preferred Eagle. In industry it is far more common to see hardware companies use Altium, OrCad, Cadence, or even Mentor Graphics. I've also heard of one company who uses KiCad.

One of the big drivers for which EDA tool suite hardware companies choose is integration/compatibility with their Product Lifecycle Management (PLM) tools. My understanding is the bigger tools have better solutions for this than Eagle.

Altium is probably the industry standard, though there are several high-end competitors (OrCAD for example). Similar to how Solidworks is usually considered the standard for CAD, but there are lots of competitors in the $2k/annum range. EAGLE was/is certainly used in production in many places, but it gained traction because it was competent and their free tier was good enough for almost all hobbyist work.

EAGLE was barely maintained for years, until Autodesk bought it and started making a lot of improvements, but the changes were often buggy and broke existing workflows. They also changed the pricing structure and many pro customers were unhappy about that too. But while a lot of people grouched about it, it's not like EAGLE was ever been a shining beacon of good UX.

It seems like EAGLE is being merged into Fusion 360 instead, so you have a unified electronics/CAD environment.

The functionality is already included in fusion360, so it's more like if Adobe stopped selling standalone installations of Photoshop and forced all their users onto cloud-oriented subscription plans (hint: that's what Adobe did).

I'd say that Eagle was more like the hobbyist's standard than the industry standard. It's what you used if you want something that would do small 2-sided boards for free.

Eagle has some "features" which will prevent it a loooong time from being industry standard.