Because international stans take HYBE side as a majority. If you look up the Korean comments everywhere, regardless, they are on MHJ side and attacking LSFM and ILLIT. Even fromis_9 who got their first hit recently ended up doing much better than both groups digitally, and a lot of knetz were saying ok they got best skills among hybe ggs, why arent they promoted more often? Digitally, BOTH groups have underperformed on Korena charts, big time. Yes that is including LSFM. Even LSFM's physical sales are much weaker than before. Both ILLIT and LSFM are still selling decent physically and will probably be fine but it does seem like they have lost the trendy status at least for now.
And do they need that trendy status? If they make enough money and have enough fans, they'll keep making music, and that's what everyone wants in the end. The numbers don't mean anything if you know they're enough.
Besides, Newjeans' case is symbolic of not only idols' rights, but workers' rights in Korea. Though MHJ isn't a good person Hybe isn't a good company either. You mention Fromis_9 not being promoted much but that's on account of neglect on Pledis'/Hybe's part, Pledis especially has a shitty track record for their groups. This Hybe/MHJ shit is for us to observe, not interrupt.
All in all, LSFM could just be losing out due to competition and as I stated before Magnetic was a GP hit, which means their success from now on if they remain favourable to the public is going to fluctuate. But they don't have to. If international fans carry both groups they'll be fine. It's about the music in the end.