Linn and Naim 'parted company' back in 1985 - do keep up
ATC know full well what they're doing and measure every speaker they make, or at least used to. These old 19's were designed that way for a reason!!! You lot may laugh because they don't look as good as Harman designed models, but with the SL driver introduction, the 50's too developed a slightly elevated upper mid balance (can't speak for the big ones in the noughties as I wasn't dealing with ATC at this time). My 20ASL pro's definitely had a similar response shape (as measured in an article on SoS I think it was) and mainly concerning the NS10 which has a seriously nasty peak above 1khz (but which worked very well on a bookshelf).
To suggest these are small 'toy' speakers is a reflection of the room size the person making the comment is used to. I suspect his favoured speakers wouldn't work in a smaller room.
Not sure if Billy Woodman designed these as he did the previous 10 and 20 models and he certainly doesn't appear to have had much input on the very latest models as I believe he's basically retired from day to day business (although he's always 'there' in the background I was told).
Here's the article I was trying to find, an 'appreciation of the NS10 plus response plots of the usual suspects of twenty years or so ago INCLUDING the original SCM 20 ASL Pro model I once owned (I doubt it was the older tower actives that were tested). The active 20ASL Pro had a bass lift adjustment which helped a bit, but by then the Vifa tweeter was showing its age in added grittiness on my pair and it was uneconomic to replace with the intermediate tweeter as it would have involved new baffles. I made good money on the sale, but these days really miss the tactile quality a decent monitor has.
https://dt7v1i9vyp3mf.cloudfront.net/assetlibrary/n/ns10m.pdf