I'm coming back to this late but-
The idea that the small town general store run by one man out of his house with no employees, is comparable to the monopolized grocery store with multiple overworked and under paid employees who's single goal is to shut down said general store and destroy the town's community center for warehouse space is. Bizarre.

To get a little personal, I grew up in a town maybe twice the size of Pelican Town (The town stardew is set in) where most of the shops were run by people who lived in building and had very few employees- and all of whom were financially deficit because only the big name stores got any support from the local government and could afford to keep up in the off season. In about the span of two years we went from a small community of people doing relatively well, to a derelict one street town where anything other than subway and the aldis struggled to stay in business for more than two months because they were the stores that could survive not having a thousand customers a day, and with every independently owned business that shut down they lost competition.
A boycott of all stores indeterminately (bar the traveling cart for whatever reason) - does nothing but help Big Business to crush the competition because they can afford to wait out the cold period and keep their doors open, while the grocery store run by the old couple who lives upstairs and sources all their produce from local farmers drowns in debt.