So it's important to note that 4chan and the "culture" born from it is fundamentally rooted in American society and culture; changes in "chan culture" were often influenced by real-world events in the US. To that end, there is for the most part no mainstream (or more appropriately "just under the mainstream") leftist political current in the US minus a moderately increasing number of socdems in recent years. "Channers," politically as well as in other ways, often sought to be contrarian and edgy: in part as an expression of ideals that would not be given a meaningful platform elsewhere, in part as a means to upset mainstream internet communities that held more conventional views/standards. Thus you ended up with, as others have pointed out, a lot of ironic racism and other "triggering" behaviors because it elicited responses. Such "edginess" was, at least at the time, not necessarily an extension of actual beliefs; 4chan and others were mostly lukewarm liberals during the Bush years and into the early Obama administration.
A peculiar thing happened though, and it was centered primarily around Holla Forums (or more accurately its predecessors) and /r9k/. Holla Forums's first incarnation was in the form of /n/-News back in 2006, and for a time it serves its initial purpose as a news board. Over time, far-right users start to collect at the fringes of the /n/ userbase, turning many news discussions into proto-Holla Forums bootlicking and idpol. Eventually that fringe starts collaborating with Stormfront and attempts to begin setting up camp on 4chan to utilize it as a platform for their activism (this was at the height of the Chanology era). moot, having openly denounced Stormfront, cans /n/ and turns it into /n/-Transportation. There are protests for a while, but the userbase eventually dissolves into the other boards once more: that far-right fringe had not yet gained the numbers to have any substantial influence on the rest of the site, but they do become literal fifth-columnists in the intermediate time. /r9k/ also appears around this time and, lacking any defined purpose as a board, begins to descend into what we know it as today.
2010 rolls around, and the News board is restored as /new/. It enjoys a brief period of being primarily news, followed by Ron Paul shilling, followed by the re-emergence of the fifth column. They once again start rallying Stormfront and other sites to begin astroturfing the board, this time with far more success. It becomes bad enough that, within a year of its creation, /new/ is shut down once more along with /r9k/. moot once again denounces Stormfront and company as part of his shut down of /new/, while stating that /r9k/'s test purpose had been fulfilled and the feelfags had to take it elsewhere. This time the shutdown was not nearly as successful, as the communities of those boards (at least the components of them that we'd recognize today) had become substantial enough that, when they dispersed into the other boards, they become such a pollutant that the site users practically begged moot to restore the deleted boards. Sure enough, by the end of the year, Holla Forums was made and /r9k/ was reborn. It was too late though: the stormfags and the hyper-betas had their fingers in everyone's pies and weren't going to just fuck off now that they had a board to themselves back. They (mostly Holla Forums) used prior astroturffing strategies to pressure more and more users to adopt Holla Forums-lite behavior (thus creating fertile ground for more adamant holders of such views) as well as low-key proselytizing that took advantage of dissatisfaction with Obama-era neoliberalism and (later) the SJW personalities that came into prominence around the time of Gamergate. /r9k/ in turn became Holla Forums's auxiliary voice and mediator to various NEET demographics site-wide.
What we see now is the emergence of an internal contradiction with the underlying current of "chan culture" whereas their views have since entered mainstream but there is a desperate desire to cling to that initial contrarian nature. Additionally, it is now laid bare for all to see the results of Holla Forums (ironically) encouraging the mass influx of non-native users; the fact that they have since become the mouthpiece of establishment neocons and alt-right opportunists who ultimately despise any characteristic that is reminiscent of the board's roots as part of an imageboard.