Abuse of Terms: "Monarchy is not Compatible with the 21st Century"

Recently I saw a comment on the Monarchists Facebook
group that deserved a closer look:

Now, readers of this blog might remember that I dealt with a
similar set of arguments a few years back. I can't say I am
satisfied with the argument I made before so this is a bit of a
redo. Now on to the Facebook post itself.

My answer would depend a great deal on whether I deemed
the question to have been asked out of a genuine desire to
understand or if it was an attempt to shut down debate. 

In either case I would first point out that appealing to the
current year, century, or era to attack a subject is a form of
Chronological Snobbery. As C.S. Lewis points out,

"In the first place he made short work of what I have called my "chronological
snobbery," the uncritical acceptance of the intellectual climate common to our own
age and the assumption that whatever has gone out of date is on that account
discredited. You must find why it went out of date. Was it ever refuted (and if so by
whom, where, and how conclusively) or did it merely die away as fashions do? If
the latter, this tells us nothing about its truth or falsehood. From seeing this, one
passes to the realization that our own age is also "a period," and certainly has, like
all periods, its own characteristic illusions. They are likeliest to lurk in those
widespread assumptions which are so ingrained in the age that no one dares to
attack or feels it necessary to defend them."

It is important to note that monarchy has never been refuted.
Starting 200 years ago monarchy has been abandoned as a
government form because of its relative unpopularity, not its
relative inferiority. And as modern research is starting to
show, perhaps this wholesale abandonment of monarchy was
a mistake.

I might in my reply be unable to resist a bit of snark. After all,
the 21st century has seen a rise in terrorist attacks, increased
state oppression & surveillance, prolonged voter apathy, the
worsening of partisan divides, and renewed civil strife & mass
displacement of peoples. At the risk of sounding like one of
those reactionary types I'd like to ask what is so good about
the 21st century? And this question needs to be asked because
in this instance the term '21st century' may be standing in for
a set of values the person has. And if it is you may actually be
able to have a decent discussion on the merits of monarchy
once the person starts looking seriously at what they believe
rather than the nearest calendar.

A related argument that is no less silly is the slogan often
formulated as 'Because its <insert current year>'. As above it
is not an argument but in this formulation it is often used to
justify doing something while the previous example is used to
justify not doing something. One reason I dislike 'Because its
<insert current year>' is that it is almost always a missed opportunity to explain your reasoning (hence why politicians
love it so much). However, it does lend itself to use by
monarchists, in certain circumstances, who want to start a
discussion:

Loyally Yours,
A Kisaragi Colour