Okinawan karate is a very diverse martial art. It became well known after it was introduced in 1930th in Japan proper by Master Gushing Funakoshi who named it “karate” – means “empty hand” – to avoid negative, for Japanese ear, connotation of its traditional name that can be translated as “China hands” (due to long-standing traditional anti-Chinese sentiments in Japan proper which are in stark contrast with long-time Okinawan China bound tradition). His school evolved into Shotokan style even Master Funakoshi himself has nothing to do with this: he advocated karate as the single martial art and was strongly voicing against its fragmentation. A few decades later the Shotokan itself has been exported and became basis for development of Korean Taekwondo, which itself fragmented into dozens of schools, styles, and associations.
Karate styles are ranging from kickboxing-like sport styles (topped by Olympic Taekwondo) to very authentic traditional schools that preserved its original Okinawan roots and combat efficiency.
Master Funakoshi was strongly influenced by Dr. Kano. He added character-building pedagogical elements to his teachings and karate was introduced into the school curriculum in Okinawa the same way as Judo was introduced in Japan. He added “do” – “karate-do” – to the art name. He implemented Judo-style color belt ranking system for his students. He met Dr. Kano and took his encouragement at the time he needed it most – when he started his teachings in Japan (Dr. Kano didn’t see Master Funakoshi as a rival, but as a fellow martial artist and educator who deserve the outmost support; a good example that not always followed).(*)
As much as origins of traditional Okinawan ryu is lost in the oral tradition, the history of the modern karate is well documented (even at times those documents are conflicting with each other).
As a martial art style, karate is emphasizing striking techniques while grappling is relegated to a support role. In many manuals, both - traditional and modern, it stated that throw won’t end a fight and, therefore, can’t be a primary technique.
This is true even in the most balanced and combat-effective styles, like Goju Ryu (in its technical set at least quarter is throws and arm-locks).
When I can argue with this notion – a powerful fast throw in a combat situation can be the fight-ending move even if it not resulted in a broken neck, but only in internal organ concussion from the hard landing – I agree that it’s a perfectly valid approach that can be base for effective strategy.
The question is why karate emphasizing striking when Judo emphasizing throwing and arm-locks?
I see answer for this question in the historic origins of those two systems.
From the first occupation of Okinawa by Japan in 17th century Okinawans had no standing army and were forbidden to bear arms. So, traditional Okinawan ryu was developed as means of survival in non-military confrontation (no body armor expected). In this environment bare-hand striking is effective.
On the other hand traditional Japanese jujutsu, that forms Judo foundation, has been developed within highly militarized Japanese society (under almost non-stop civil war) and addressed first of all needs of the battle-field fight when sides are wearing protective armor. In this environment bare-hand striking is meaningless when throwing became very effective (as reduced agility of armor-clad man makes him more vulnerable on the ground even throw itself was not very damaging).
As military moved into the modern age and abandon the old style body armor, striking techniques became effective in the military H2H environment too. As the result in the 20th century we saw steady displacement of Judo from military training by karate, as developing combat-effective throwing skills is a much more complex and time consuming process than teaching basic striking (for H2H military training specifics look this page).
As of nowadays both – traditional Okinawan ryu and Judo – are effective combat and self-defense systems. At the same time sport versions of karate are just sport (on a par with kickboxing) and need to be supplemented by specialized self-defense training to be combat effective, as any other combat sports.
(*) I know that it's not that simple: the process of introduction Okinawan ryu in Japan and changes to conform to Japanese martial art tradition (exemplified by Judo and kendo) started well before Master Funakoshi arrived to Japan and before he met Dr. Kano - good condensed overview of this history can be found in commentaries by Patrick McCarthy to his translation of Bubishi, - but in mid-1930th Funakoshi was the public face of Okinawan ryu in Japan.