Where was the writer of the article gardening?
Maybe somebody will tell you the right way to do it in wouthern zone 8.
Meanwhile I'll tell you what I do. I've never had a 'multitude' of coneflowers from self seeding.

I let everybody bloom as they will. I deadhead early on when booms are sparse. When bloom is full, I stop deadheading.
A few earliest cones will turn black ahead of all the rest. I snip those off and smush the whole seed head into the ground, a trick I read about here some years ago.
I pull the pine straw back to give the seed a little growing room.

Most blooms are beginning to look old and ratty and I will soon cut the whole mess back to about 6-8 inches tall after I gather those black cones.
In a very few weeks there will be rebloom on the pruned plants. Sometimes it's the next spring when the new plants appear.

Nell

Once again I owe you thanks, Nell. I'm in that 'needy' gardening stage...I seem to need very detailed tips on the simpliest topics! But it is certainly wonderful to have people to turn to for advice. What you said makes perfect sense and I'll give it a try, too. :)

-Sharon

I deadhead all through the season, which keeps the plants looking good and in constant bloom. I don't cut back until late fall/early winter. If I have volunteers the next spring I just move them to another location.

I have a ground cover instead of traditional mulch. And where there is some bare soil I use compost for mulch, so seeds come up without a problem.

Diana

Regional differences, big time, Diana.
I deadhead echinacea all through May, let it go in June, cut back in July when the foliage gets tall and lanky and ratty in the heat. There's new foliage already coming up at the bases. They come right back and bloom again from August through October. Sharon might want to treat some of her plants both ways.

I get paranoid. After I wrote the above, I thought, "Do they really bloom in May? Do they really bloom to the end of October? I had to look up pics to reassure myself.

What ground covers do you plant?

Thanks,
Nell