Shoes for lighter runners vs heavier runners?

Why do reviewers classify shoes like this? It doesn't make sense.

I come across this every time I look at the Altra shoes I like (Superior, King MT, Escalante, etc.). They just about always give this caveat for these models: for lighter runners and shorter distances.

That's simply not true. If you're used to this kind of shoe, it doesn't matter how much you weigh or how far you run. 

For instance, I'm so used to the models I like, I can't even wear Altra shoes with more cushioning.

They cause fasciitis plantar in one foot similar to if I wear shoes with big drops. I think it has to do with the shoes being less flexible. Either way, I'd destroy my feet in those shoes the reviewers say are meant for longer differences.

It would make more sense to say shoes for more experienced or efficient runners, runners with good technique, or even faster runners. But even then, I'm not sure. I think it's just what you're used to. But never heavier or lighter runners.

Surely a 60 and an 80 kg runner with the same BMI running at similar relative speeds --- everything else being equal --- would fare just as well in the same model and style of shoe.

But maybe heavier or lighter runner is a euphemism for overweight versus trim. That might hold more water.

Anyway, I wish they give up the trite caveats.

Altra Superior 4.0 vs Altra Superior 4.5

Doing nearly 1000 km on a pair of shoes is as good an excuse as any to get a new pair. So last week when I saw I'd done 993 km in my Altra Superior 4.0s, I jumped on Amazon to order a pair of Altra Superior 4.5s.

Not that the 4.0s look or feel like they need replacing. They've not showing much signs of wear, and I'm not going to retire them yet. I'll rotate them for trail runs with the new Superiors and my King MTs. I might use them for faster trail runs as they are lighter and do feel nimbler than the 4.5s.

Old meets new! New Altra Superior 4.5s (left) and 4.0s with 993 km (right)

The same with more padding

The 4.5s weigh 280 grams versus the 245 grams for the 4.0s (US size 11). That's quite a big difference.

I'm guessing most of that extra weight has gone into the extra padding you feel around your foot. (Is that what they call the "upper"?)

For me that has meant a better fit with the 4.5s. I got a blister on the heel of my slightly smaller foot when I started wearing the 4.0s. I felt a warm spot in the same place on my first longish run in the 4.5s, but it never went any further.

The 4.5s feel quite stiff, too. Stiffer than my 4.0s right now at least, but that might be because the 4.5s are newer. Regardless of whether the 4.5s are actually stiffer or not out of the box, hopefully they will soften with time.

In any case, in this update there's not too much change to a shoe I've enjoyed running in. Thank you, Altra! I'm still a fan.

(I currently own six pairs of Altras I run in --- the three trail shoes I mentioned above plus two pairs of Escalantes 1.5s and a pair of Altra One 2.5s. I've worn nothing else since I bought my first pair of Altras (the Superior 1.5) in 2014.)