Here is a slightly more "recent" ad -- Sweden, by way of Germany -- well in excess of three decades ago (considering the regulators shown) -- and probably among the earliest example, I had seen, of the true dumbing-down of both product advertisements and that of user manuals. Nowadays, it's not uncommon to see those publications, printed in large blocks of green, yellow and red, to aid mouth breathers, in taking into account, what I can only assume, are traffic signals.
Prior to that time, there were often full breakdowns of internal parts (see below, from the 1970s); their catalogue numbers; and a full written rationale, in multiple languages, on the proper use of the devices and their accessories -- even to the extent of the swapping out of bodies (in the case of the Poseidon Cyklon) for full-face mask, or even firefighting use, back in the day -- not just some dipscheiß red "x" on an ad for a Frostschutzkappe (an "antifreeze cap"), to dissuade someone, without any further explanation . . .
Prior to that time, there were often full breakdowns of internal parts (see below, from the 1970s); their catalogue numbers; and a full written rationale, in multiple languages, on the proper use of the devices and their accessories -- even to the extent of the swapping out of bodies (in the case of the Poseidon Cyklon) for full-face mask, or even firefighting use, back in the day -- not just some dipscheiß red "x" on an ad for a Frostschutzkappe (an "antifreeze cap"), to dissuade someone, without any further explanation . . .