Why software developers are against marketing Dev-posts?

What kind of "posts written for developers" are you referring to? Since the dawn of software, there's been disagreement been the sales and marketing people and the developers and support folks. Usually the issues are around salespeople incorrectly describing or over-selling the product, leaving devs and support people hold the bag after something less-than-desirable is delivered.

It's difficult for non-tech people to write highly technical information that is accurate. Programming documentation, especially, requires people who understand programming. Sadly, many of the best tech folks are not good communicators or marketers because their writing lacks impact and interest.

We'll always have some version of this disconnect.

As I got my job in an IT company I often hear that the developers do not like the posts written for them which are coming out of the marketing teams. Is it right to hear that opinion? I think that all the posts, wherever they are coming from (developers, marketers, business side) are written to help someone to finish their job or learn something new, even the promotional ones. Very often you can read posts written by marketers that are highly professional and helpful to developers. Also often the developers can share something that is useful to marketers.