It's hardly back to square one, and saying that she's back at the start ignores her character development. Firstly, her dragons are old enough and big enough to destroy entire cities which means she's got the upper hand on her old self. Second, as soon as Drogon turns up, which I imagine he will at some point this season, I imagine the Dothraki will just bow down to her out of fear. Loyal army + dragons = good times for Dany.
Also, you're ignoring a pretty huge prophecy told to Dany by Quaithe, that pretty much explains why she's had to "go back" to the Dothraki: "To go north, you must go south. To reach the west, you must go east. To go forward you must go back, and to touch the light you must pass beneath the shadow." That quote is from A Clash of Kings, which was published in 1998, at least a decade before the TV show was even thought of. Her storyline hasn't been delayed for TV ratings, it's been plotted for almost 20 years.
Also, because of the location of King's Landing and Slaver's Bay in relation to the Narrow Sea, far too many people have presumed that she'll attack Westeros from the east, but what if she's supposed to go to Asshai (the most southern, eastern city in the Known World) and attack Westeros from its west side? GRRM has stated many times that the Game of Thrones/A Song of Ice and Fire universe is spherical, much like our own world. There's no use making judgements about a character's storyline until it's finished and, as we all know, Dany's still has some way to go.