The VN industry has a long-standing market of Japanese porn titles that now exists side-by-side with an emerging market of western SJW-centric titles. Some of said hentai titles are story-heavy VNs with occassional sex scenes added in (they're the kind that can easily get ported to consoles with sex scenes removed), while other titles are all about sex scenes with less focus on story (they're called "nukige").
Most eroge, like most VNs, stay inside of Japan. Thanks to the rise of Mangagamer over the past few years, however, more eroge titles have been coming to the west alongside non-eroge VNs. The successes of more "mainstream" VN and VN-style games such as Danganronpa, Corpse Party, and steins;gate has in turn made localizing eroge VNs more feasible than before.
If we imagine the VN industry as a country that the SJWs are in control of, then from their perspective, the eroge market is to the VN industry like Guantanamo Bay is to Cuba; It has been constantly shunned and its legitimacy has been come under question at every possible corner.
SJWs and pro-censorship weebs have been trying to subvert the eroge market in the west for years. A few of them might be open to story-centric eroge being brought over, but then they're often the guys that look down upon people who buy nukige and defend acts of localization-induced censorship, such as when titles like Family Project (pictured) or Shiny Days had content censored when they were brought over. A classic example of this is illustrated here:
The person who wrote this goes by the username "dark_shiki" in the JAST USA forums. Dark_shiki is a longtime fan of story-centric VNs, and has a history of expressing support for JAST USA in their forums whenever they censor a title.
In his pro-censorship arguments, he frequently uses contradictory stances on censorship (e.g.–"I don't support censorship BUT…"), using poorly-researched legal arguments (e.g.–He basically believes obscenity laws are blanket bans on specific kinds of content), using the relatively small scale of censorship as an excuse for its existence, and appealing to getting the VN market mainstream to justify censorship.
Dark_shiki is a textbook example of a pro-censorship shitlord within the VN community and the weeb fandom as a whole. Whether he's an SJW may be up to debate, but a lot of the arguments he uses to justify censorship of eroge is in line with what SJWs would typically say when it comes to localization-induced censorship.
So where does loli come into the picture? It's practically at the heart of the issue when it comes to localization problems in eroge. The opposition to loli, or the perceived opposition to it, is often cited as the main reason when a company decides to censor or pass on an eroge title for a western release (DOAX3-style BS is practically commonplace because of this). The SJWs and the white-knighting pro-censorship weebs defend their decisions at practically every corner and drown out the people that oppose this sort of crap.
In order to weaken the SJWs' and the pro-censorship weebs' grasp of the VN market, we have to be willing to support and expand the eroge sub-market. This means inevitably defending and supporting loli, including but not limited to getting western companies to localize eroge with loli content.
We can't just ignore the eroge market and allow anti-loli sentiments to fuck it up, because the entire VN market is intimately tied to various other segments of the weeb market, such as anime and manga. This includes the eroge market as well. A good deal of anime/manga titles that have seen success here (Fate/Stay Night, Shuffle, etc.) actually started out as eroge titles.
You let the VN market fall and get censored by SJWs/pro-censorship weebs, then the markets for anime, manga and other Japanese games become vulnerable, because they can cause drama big enough to spill into said markets.
We already saw this when the SJWs made a huge stink with Rapelay in 2009: Not only did JAST censor Family Project, but the controversy caused Funimation to initially consider censoring their DVD release of Dance in the Vampire Bund for loli content before fan outrage prompted them to reconsider. You can also bet your fucking ass that NISA took this sort of shit into consideration when they decided to censor more recent titles like Mugen Souls or Criminal Girls, assuming they themselves haven't been co-opted by SJWs already.
Loli porn is the first line of defense when it comes to keeping localized weeb titles uncensored in the west. You let it get censored by SJWs, and they'll be going after all kinds of other "problematic" content in titles released from Japan.