Like others wrote, there's no longer a standard for what the measurement actually means. Most structures aren't actually 7nm in a 7nm process.
For example, a typical metal pitch on the low metal layers is 40nm, meaning you get one wire every 40nm, or 25 wires in parallel in a 1um channel.
What Intel is calling 10nm does indeed appear to be close to the others' 7nm. Then again, Intel is seriously behind on 10nm, so the bottom line remains the same: they seem to have essentially lost their process advantage.
Then why do they continue to use it at all? It's like measuring your electric car in the number of pistons it has. We all agree process node numbers are meaningless now so why do we keep using it?
How about a number that actually relates to the performance and can be measured?
My best guess is a combination of historical inertia and the fact that the names are actually meaningful, just not in the way that one might naively expect as an outsider.
When the foundry sends you a design kit which contains all their design rules and tooling around a process, then this process has some codename that appears everywhere (think filenames, names of library elements, and so on). This codename tends to be something like GF14 (for GlobalFoundries' 14nm) or N7 (for TSMC's 7nm) plus cryptic suffixes for different revisions of the foundry process.
So the 14/12/10/7nm terms are actually part of the design engineers' everyday work flow. They just also filtered through to marketing for whatever reason.
I could imagine that at some point in the future, foundries will switch to a year-based versioning similar to what happened with a lot of software. So you'll have a GF2027 process and so on. That's pure speculation on my part though, and inertia is definitely a thing.
For example, a typical metal pitch on the low metal layers is 40nm, meaning you get one wire every 40nm, or 25 wires in parallel in a 1um channel.
What Intel is calling 10nm does indeed appear to be close to the others' 7nm. Then again, Intel is seriously behind on 10nm, so the bottom line remains the same: they seem to have essentially lost their process advantage.