I'll leave GP to answer the outrage comments, but I think the rest reasonably calls out for perspective.
Merrick Garland wasn't just not confirmed, his nomination was ignored for 9.5 months. As you point out, it's not uncommon for opposition party senates to turn down supreme court nominees, as is their due. It is, however, extremely rare for them not to hear those nominations at all, and Garland's nomination timeline stands out for its longevity.
Out of 163 nominations, only 11 have lapsed (from your wiki link, which lists an incorrect count in the summary). Reverse chronological order of the most recent 5:
- Garland (2016): 293 days. Opposition senate.
- John Marshall Harlan II (1954): 27 days in lapsed nomination + 49 days for confirmation. Ally senate, confirmed by opposition senate.
- Pierce Butler (1922): 14 days lapsed nomination + 16 days for confirmation. Ally senate.
- William Hornblower (1893): 45 days lapsed + 41 days to reject confirmation. Ally senate.
- Stanley Matthers (1881): 36 days lapsed + 59 days to confirm. Opposition senate, confirmed by split senate.
The point being that there is essentially no historical precedent for this behavior, to the point that we need to look 135 years in the past simply to find any example of an opposition senate delaying a candidate's nomination. Even then, Garland is the supreme court nominee with the most time under nomination in US congressional history by a factor of more than 2.
> over the history of USA 29 times supreme court judges were nominated in election year
This doesn't really do justice to the history here, 1/4 of those nominations happened in a single year due to conflict between President Tyler and the Whig party, and an overlapping 1/4 were withdrawals. The last ~170 years of supreme court nominees have been pretty uninteresting and undramatic.
- Garland (2016): lapsed. Ally senate.
- Fortas (1968): confirmed. Ally senate.
- Thornberry (1968) withdrawn because the seat was no longer available, due to some musical chairs replacing Chief Justice Earl Warren. Ally Senate.
- Murphy (1940): confirmed. Ally senate.
- Cardozo (1932): confirmed. Ally senate.
- Clarke (1916): confirmed. Ally senate.
- Brandeis (1916): confirmed. Ally senate.
- Pitney (1912): confirmed. Ally senate.
- Shiras (1892): confirmed. Ally senate.
- Fuller (1888): confimed. Opposition senate.
- Woods (1880): confirmed. Opposition senate.
- Hunt (1872): confirmed. Ally senate.
- Chase (1864): confirmed. Ally senate.
- Bradford (1852): lapsed. Opposition senate.
- 7 various nominations (1844): none confirmed. Opposition senate.
- Crittenden (1828): postponed i.e. rejected. Opposition senate.
- Johnson (1804): confirmed. Ally senate.
- Ellsworth (1796): confirmed. Washington was president and rejected party politics, but the Federalists were friendly with him, so ally senate.
- Chase (1796): confirmed. Ally senate.
- Cushing (1796): confirmed. Ally senate.
I think there's plenty of evidence that Garland's nomination fight radically rocked the boat in US national politics, and we're likely to see similar boat rocking over the next few years as Democrats are pushed harder to abuse the limits of their power in order to improve their leverage on Republicans.