"Have we lost the ability to focus?"
Some of us have. And some of us always will, for one reason or another. When people lay down The Law -
you know - those hard facts and certain truths - sometimes, they'll necessarily be turning their backs on another focus. Sometimes, they'll be ostensibly
or literally
blind to a better focus - one more worthy of our gaze. Weasel wording wonders, they sometimes may
be. If they're
not, they could possibly get out a bit more., socialize a bit, with the hoi polloi, the
great unwashed. Stray from your path a
little and you're likely to discover
others.
Some people for instance, those who play some of the more challenging computer games available, have an immense ability to focus, like elite athletes or soldiers or scholars do. These are the types typical of people now under the spotlight - and gaming, game theory, and
learning is, today,
occurring - sometimes, in
epic proportions. Often, this sort of thing's been going on for
decades 
So, it's
safe then, 'though I may be mistaken, to bellow an emphatic "
No.", in answer to the OP's question. We haven't lost our ability to focus. Some of it just may sometimes be a little
misdirected
Keeping to the question, grammar and typographic errors are really
no real, steadfast indication of a loss of focus either. Sometimes, words left out, or left
in, are an indication that editing, to a degree, is
present. Sometimes, people do this stuff just to frustrate the incurable pedants, sometimes as a more
insidious provocation. Not very nice. Sometimes, we're,
many of us, just
plumb-tuckered-out - nothing left in the tank for
any redrafting.
But
most times, thinking and striving for better ways to say something presents other challenges in the flow of logic in the vicinity - points attained can be softened or corrupted in the ensuing confusion and
this can be easily missed by the sometimes, but not always, lazy, sometimes, but not always, time-poor author. Small screens, 'noise', baby buttons, fading eyes, a less-than-conducive domicile, and crossfire are also culprits,
sometimes 
- a lack of focus in another sense then, attractions, refractions and distractions, duly warranted
Another point, before I pull the ripcord: Having good ideas is not solely the domain of the erudite, although some would dearly like it to be that way, for one reason or another,
again.
Anyone can have good ideas,
great ideas. Getting the message
across then, is the
fun part. Learning about the intricacies of language helps but, by hook or by crook, we should always make the effort. Communicate. And, good grammar
be dammed.