About two decades ago, there was a push by an alliance of sex-negative feminists and social conservatives to ban lolicon (and its BL equivalent shotacon) in Japan. This came about at the same time as a movement in the United States to prosecute more aggressively cases of "obscenity", chiefly fictional representations of children (or apparent children) in sexual situations, leading to such absurd cases as a man tried for possession of Simpsons parody cartoon porn. Aged only 13/14, I started to defend free speech online against such attacks.
One case that was of some importance in turning the tide in favour of lolicon was that of Kodomo no Jikan, an otherwise non-erotic albeit risqué manga series—authored by a female mangaka, with a story told from a female perspective—that was banned and demonized in the West, largely because of a single scene showing 9-year-old Kokonoe Rin masturbating with a detachable shower head (the naughtiest bits were tastefully hidden, but it was still darn adorable and super hot if you ask me), in addition to other "objectionable" elements such as AAM Rin using the threat of sexual abuse accusations to blackmail her teacher-slash-romantic interest. [See Note 1]
Other popular non-erotic series that veered into "dangerous" territory include Puni Puni Poemy (briefly banned in New Zealand for supporting "the exploitation of children and young persons for sexual purposes") and Crayon Shin-chan, in which the titular character, a 5-year-old boy, engages in irreverent and non-sexual mooning and genital display with adults (quoting Fandom "the naked butt dance and the mister elephant dance"). The lesser-known series Kite is banned in Norway for its graphic depiction of a teenage girl being sexually assaulted.
The truth is that lolicon and erotic anime & manga have gone hand-in-hand from their inception, in much the same way as Japanese drawn erotica dating back to the ukiyo-e era already involved "tentacle rape" (a staple that any fan of so-called "hentai" knows well). Cream Lemon, the second erotic anime series to be released, includes several lolicon episodes, and the very first erotic anime altogether was in fact Lolita Anime, which is strictly and exclusively lolicon (and quite perverse, too). Both date back to 1984, ironically enough—hurray for thoughtcrimes!
Where am I going with this?
I believe there are many useful parallels to be drawn between the case of lolicon/shotacon versus anime & manga in general on the one hand, and adult-child sexual contact versus interpersonal sexual activity in general on the other hand.
Legal authorities reluctantly and begrudgingly decided to tolerate lolicon/shotacon because the broader population of anime & manga fans pressured them to do so. Alone, the fans of such content could never have won this fight. The best allies of lolicon/shotacon fans were/are the people who enjoyed works, such as Kodomo no Jikan or Puni Puni Poemy, that fell into a grey area and would likely have been prohibited by the strict legislation that was being put forward.
My belief is that MAPs should actively seek the allyship of the broader population of people who really love sexual intimacy, in particular those who enjoy or might enjoy anything that falls into a grey area: age play between consenting adults, relationships between adults and teenagers who are obviously very mature mentally [See Note 2] yet have not reached the age of consent, relationships across different jurisdictions where the minor is above the age of consent in his or her jurisdiction but not in the adult's, and any other such controversial case you may think of that lies at the boundary of social acceptability and legality.
Self-interest is the most predictable of motivators. If we convince people that their own sexual choices and practices are under threat, we might be able to convince them that they should be contributing to our cause. I believe that it shouldn't be too difficult to make the case that the situation has been getting steadily worse with respect to people's sexual freedoms whenever a "child"—real or imaginary!—is involved.
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Note 1: Kodomo no Jikan is actually pretty good at exploring the moral, philosophical, and practical implications of child-adult romance, as well as the underlying personal and psychological reasons for the main character being as precocious as she is and having such emotional needs (she's an orphan) and sexual desires.
Spoiler!
Note 2: Many teenagers accomplish great things. At 16, I was already attending university with top marks, yet in some jurisdictions I wouldn't even have been considered capable of consenting to sex with many of my classmates (those "too old")! I'm not even an especially remarkable example: others have done the same while years younger than I was. Even if one looks at sexuality specifically, I know many boys and girls who have already had multiple sexual partners by the time they're 14. Why should they be restricted to a narrow age window of fellow teenagers with mostly limited experience?