it's usually just joking about it.
Considering the relative frequency with which stranger notions get espoused 'round these parts in complete seriousness... kinda hard to tell.
Especially as it cleaves real close to certain mindsets not infrequently encountered among "shippers" online.
Yeah, but "shipping" is notorious for proposed ships that at first are presented as obvious jokes later turning into dead-serious ideological conflicts. Like many of the headcanon-based general interpretations people generate around here, top-bottom wars and shipping wars tend to share the attribute of being based on the most strained, lemon-squeezing readings of very slight suggestions in the text, or more often, on no textual evidence at all.
In the case of Bright and Cheery Amnesia, the very first thing we learn about their sexual relationship is that Arisa was the one who usually "initiated things," and in Chapter 1 (after Chapter 0) we learn that Mari usually waited for Arisa to kiss her in the mornings.
https://dynasty-scans.com/chapters/bright_and_cheery_amnesia_ch00#8
So whatever the peculiarities of Dynasty commenters might be in regard to the issue of tops and bottoms, they have little to do with the theme as presented in this series.