Executive producer Bob Boyett told People magazine exactly why the two stars -- who once played Michelle Tanner -- won't be featured.
"Ashley said, 'I have not been in front of a camera since I was 17 and I don't feel comfortable acting,'" he told the magazine. "Mary-Kate said, 'It would have to be me because Ash doesn't want to do it. But the timing is so bad for us.'"
He added that the twins' fashion line also conflicted with filming of the show.
John Stamos said he understands why the Olsens can't appear in the reboot.
"Lori [Loughlin] was talking to me about the twins and said, 'They just won a CFDA award.' And I'm like, 'Yeah, that's like winning an Oscar.' It was them and Tom Ford. I get where they're at," he explained.
The Olsen twins, 29, were not even 1 years old when the show started filming back in the mid-1980's.
Dave Coulier added, "I think they have a different perspective. When we get together and we reminisce, they were babies [at the time]. So they don't share those same memories."