Arguably, one reason that science is so successful is that it is a very conservative and insular operation. By concentrating enormous resources on solving the puzzles that are on the immediate frontier, scientists are able to make steady advances and occasional breakthroughs. The cost of this focus on current puzzles is a neglect of foundational questions, anomalies, and unconventional ideas. Typical working scientists have a hard time keeping up with conventional research in their speciality. There are experiments to be done, grant applications to write, papers to be written, seminars and conferences to attend, and perhaps teaching to be done.
Research is very competitive.
Delay may mean losing out to others in the field. It may mean loss of a publication, a job, a promotion, perhaps a discovery. In this context, many scientists do not want to waste their time looking at someone else s claim to have made a breakthrough, unless it is a top person in the field. Most likely, the alleged discovery will turn out to be pointless or wrong from the standard point of view. If the outsider has made a genuine discovery, that means the outsider would win rewards at the expense of those already in the field who have invested years of effort in the conventional ideas.