Paramount determined the number of episodes that were ordered each season, not Berman.Hell, the only reason Star Trek was doing 26 for as long as it did was because Berman was so obsessed with selling the shows into syndication, but even that doesn't mean the same thing it did twenty years ago.
There's no reason a 26 episode season isn't possible these days. You wouldn't need to produce an entire season before initial airing. It's a financial decision on the part of now vertically integrated network/studios to save money. In the old days, an episode was debuted and repeated once, but in recent years, ratings for repeats have tanked so badly, it's cheaper to preempt for sports or a special rather than take a hit on airing a repeat and dragging the show's (and the network's) ratings adverage down.26 would be possible if the show had a season completed already before it aired and a second season already being written and possibly in post production, that way the series can have a year of playing room to write and produce more episodes and not worrying about getting them completed and aired in time.