I totally agree with Anjali & Manmohan but there are some alternative possible reasons that 3rd party app posts which have not been controlled does not perform well.

• When using a tool or scheduling posts, people create very less engaging content.
• Real time event posts are not being timely posted using 3rd party apps.
• Image Optimization for every social social media platform cannot be done through 3rd party apps.
• Very few posts are likely to get engaged that looks automated, that's why tools like IFTTT performs very badly in terms of engagement.
• What's the benefit of scheduling content for later when the story or information has already gone viral & will not have so much of importance also which was at the time of scheduling.

In my opinion there is no solid evidence beyond people's "based on hearsay" experiences to support the claim. You can use whatever you like.

Is the Social Media reach impacted by 3rd party apps?

Yes definitely, lets say if a company putting time ,money and effort into creating new content, might we assume that these companies want that content to be found,shared and acted upon? It is an easy jump to make then that these business, which are spending money on content creation, will have no problem if they spending money on tools if they saves them and of course want to have this content reach as many people on facebook as possible. But the facts is that the use of third party apps used to be penalized on Facebook. The impact on reach used to be large ,decreasing reach significantly.

I agree with Ashish that third party publishing tools/apps are not penalized, not at least on Facebook. There was a study conducted over a year ago, clearly showing that posting using a 3rd party or natively won’t affect your reach or engagement on Facebook.

Some top brands have already been effectively using Buffer, Hootsuite  or Adobe social as their third party posting tool to get better reach. However, the kind of content you share on social media is still very important when it comes to higher engagement, regardless of third party posting or native posting. This is perhaps the reason behind the much-spread nagging on the internet that third party posting lowers down reach and engagement. Actually, it's bad content which is responsible. People who create social media posts sometimes tend to care less in creating content that is supposed to be posted by third party apps/tools. In the nutshell, the adverse impact comes from low quality content, not from third party posting. I hope this answers the query.

No, there is no evidence of social media sites penalize the posts from 3rd party apps.

Native post is always been stronger than scheduled post. We always see better percentage in live posting rather than scheduled posting. There are lots of creative products out there, i would prefer IFTTT rather then native post.

There are some best practises for IFTTT such as :

Email:

It helps to save attachment to the google drive. We dont need to check the email box again & again. We can also postpone answering the messeges & emails using this tool. Useful content such as project feedback, contact number's can be preserve directly to evernote. The best thing is getting a notification while recieving the high priority email.

Social Media:

It helps to publish instagram post as twitter post & sychronise the instagram & twitter accounts. This tool works for sharing the post & connect to all social media platforms such as Twitter, Facebook & LinkedIn. We can easily share facebook post to the twitter.

A lot of features this tool consist of :

• We can share top SEO post on Reddit
• Reject spam emails
• Can Tweet WordPress blog post.
• Can create WordPress blog post from Evernote notebook.
• Vimeo video can be worked as WordPress blog post.
• Can save Instagram post to Dropbox folder.
• Can share WordPress, blogger post to Linkedin.
• Can save every tweet, new twitter followers to google drive.
• Share Instagram pics to twitter.
• Can schedule post from Google calender
• Can set up content marketing radar station slack, twitter advanced search & IFTTT.