Yes, it's probably because this is a proven business model and if you niche-down enough, you will be able to serve the audience better than the bigger competito

Yes, it's probably because this is a proven business model and if you niche-down enough, you will be able to serve the audience better than the bigger competitors. The biggest problem though is still bootstrapping the demand side (job seekers) of the platform (supply side is fairly easy, as you can even handpick the initial jobs). We (https://swissdevjobs.ch https://swissdevjobs.ch & https://devitjobs.uk https://devitjobs.uk) started with articles how to migrate from other countries to find a job in Switzerland / UK and at some point the organic traffic picked up (but it also took years, as in the case of japan-dev).