Marcus theory describes the rate of electron transfer reactions, where the species involved do not undergo large structural changes. When $$\Delta\text{G}$$ becomes more negative, Marcus theory becomes inverted, and the likelihood of electron transfer becomes less likely. This is because the energy change that would occur during that electron transfer would release large amounts of heat. As the reaction process wants to minimise the heat lost in a chemical reaction, smaller and favourable reactions are preferred (and so smaller electron transfer reactions are more likely, as opposed to direct charges recombination).
The is observed in photosystem I, where the smaller, energetically favourable electron transfers are favoured through the photosystem instead of a direct charge recombination from chlorophyll to P700.