The Watergate comparisons fail on key points with the Russian theory

Adam Mill:

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In the Watergate scandal, the burglars were discovered by a hotel security guard and arrested by local police on the very first day of the scandal. On day 90 of the Watergate scandal, a grand jury indicted the Watergate burglars plus G. Gordon Liddy and E. Howard Hunt, two of the break-in organizers.

In contrast, the 2016 DNC cyber burglars, whoever they are, have never been arrested or indicted. In fact, the DNC has refused to allow law enforcement to inspect the crime scene—i.e., the server itself. The conclusion that Russians hacked the DNC server relies solely upon the opinion of DNC-funded Crowdstrike, a firm hired by Perkins Coie, which also hired Hillary Clinton- and DNC-funded Fusion GPS to conduct opposition research on Trump.

Perkins Coie and their contractors were hired to help Clinton “achieve [her] electoral and strategic objectives.” They were not in the business of investigating crimes. There is no public report of the DNC paying the key investigators in the Watergate scandal.

In July 2016, WikiLeaks published the first batch of emails hacked from the DNC server. One logical point of investigation might be to interview WikiLeaks to see what, if anything, it has to say about the source of the stolen DNC emails. As of December 13, 2017 (day 604 since the DNC server break-in) Mother Jones reported the special counsel had made no contact to ask where WikiLeaks founder Julian Assange got the emails.

Assange denies receiving the emails from a Russian source. A nonpartisan group of former intelligence officials has published a report disputing that the DNC servers were hacked over the Internet. Based on the download speed of the stolen emails, the group concluded that an insider likely caused the breach.
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There is much more.

The Watergate special prosecutor was appointed by the Attorney General and approved by the Senate.  Mueller has not been approved by the Senate as required by the constitution.  If he gets any convictions those convictions will likely be challenged in the courts by this defect.