and how do you know that exactly ?
Sony at least had somewhere to start - they've been making full-frame, pro-standard A-mount lenses for years - and teamed up with Zeiss, yet they're still only getting there slowly. Displacing Canon and Nikon, with their established stable of high-grade lenses, is a tough job, and convincing Sigma, Zeiss and others to make high-grade lenses for E-mount is equally tough.
Panasonic is essentially starting from nowhere, apart from a few M43-sized consumer-grade lenses. They're teamed up with Leica, but not only need to break into the full-frame market, but displace Canon, Nikon
and Sony, who all have big head starts against them.