They were thought of earlier, or arguably, at almost exactly the same time:

• The Japanese began construction of the Satsuma in May 1905, several months before HMS Dreadnought. She was a "semi-dreadnought", incorporating and all big-gun armament of mixed 12in and 10in guns (although originally designed with an all-12in gun design, which was adapted due to cost limitations) but still powered by triple-expansion steam engines rather than turbines.

• Italian naval designer Vittorio Cuniberti had already espoused the "all big gun" concept in 1903 in his ideal battleship design, 2 years before the battle of Tsushima took place, and approached the Italian government with such a design which was rejected on cost grounds.

• The US Navy had been tendering "all big gun" designs from around 1903 onward, which would eventually emerge as the USN's first dreadnought class, the South Carolina. Although they were once again powered by expansion engines rather than turbines, they arguably possessed a far more advanced gun layout ("superfiring"), which would in time become the standard layout for dreadnoughts the world over, although the characteristic beam turret layout championed by HMS Dreadnought would prove hard to shift for other navies.

So dreadnought arguably didn't really do anything that was totally unheard of: All big gun armament was being mulled as the next step some years before, and steam turbine technology was cemented as a viable future propulsion system since the end of the 19th century, although originally for small high speed vessels such as torpedo boats and destroyers. What the Dreadnought design did do was take all those ideas, combine them into a working warship, and get that design into service in blisteringly fast time. HMS Dreadnought was constructed at an astonishing pace, leaving the slipway in 5 months and fitting out in another 10, which pulled the rug out from under the navies of other countries who had either semi-dreadnoughts sitting on slipways half finished, or full dreadnoughts existing only in the minds of designers.

Other nations did not feel the same impetus for economic reasons, such as the Italians, technological reasons, such as as the struggle the embryonic Japanese gun and shipbuilding industries would and did have meeting such demands, or simply because the slipways were already filled with the current battleships being finished, and new designs would only be considered when the current round of building concluded, as building a battleship was not something that can be taken lightly, unless of course you are the worlds premier naval power and have the shipbuilding capacity and sheer balls to render all your pre-dreadnoughts useless, because you know it also renders your rival navies obsolete and leaves them playing catch-up. Dreadnought reflects this point well as she possessed plenty of odd and awkward design choices and flaws, such as the position of her spotting top behind the first funnel and her generally weird turret layout, flaws that would not be immediately corrected as the following dreadnought classes of the Royal Navy would remain outwardly similar (although with improvements), up until the Orion class superdreadnoughts, which finally dispensed fully with beam turrets.