Raspi - definitely

Arduino - hmm, I don't think so. Arduino seems to have made it a lot easier, but Arduino used a pretty open platform from the start, so it didn't remove any hard barriers to entry (compiler/tooling). Arduino (on AVRs) always used AVR-GCC and AVR libc, which came before Arduino/Wiring. AVRs also had free/open tools for programming before Arduino (parallel port programmer and other DIY tools).