I'd agree that sugar isn't the only thing to blame - there's a lot more nuance, and increased sugar is only one of the many negative environmental/lifestyle changes affecting modern metabolic health (increased meal frequency, lower quality of sleep/circadian disruption, food processing and hyper-processing, and sure, hormone altering contaminants in the food and water supply all play a role. Also, speculatively an unprecedented increase in the consumption of PUFAs), but I think it's still worth noting some caveats to Guyunet's graph that you link to:

* While sugar (sucrose from sugar beets and sugar cane) has decreased since 1980, this is largely because of a switch to non-sugar caloric sweeteners, initially HFCS, and a range of others (I've noticed agave being pretty popular in "health" foods for example - while it has a slightly lower GI, it's actually more calorically dense than sugar: https://www.sugar.org/wp-content/uploads/Sweeteners-in-Food_...). Note you can look at a graph of the intake data from the Sugar Association (a sugar industry site) that shows that total sweetener consumption remains quite high: https://www.sugar.org/diet/intake/ (data is sourced from the USDA)

* While these are aggregate/average numbers, and obesity in the US continues to grow https://www.cdc.gov/obesity/data/adult.html (41.9% in 2017-2020 data) - a declining overall consumption may mask a divergence between a decrease in healthier and increase in unhealthier populations - it's hard to separate that out because the data isn't broken down between the USDA consumption vs NHANES health data populations.

* A lot of the "sugar consumption is declining (or soda consumption is declining) so it can't be the problem" proclamations are also being masked by the aformentioned caloric sweetener replacement, and in the sugar sweetened beverage (SSB) replacement - less soda, but the same sugar consumption via sweetened teas or juices, sports drinks, etc. Here's the CCD data on SSB conumption, which remains grim: https://www.cdc.gov/nutrition/data-statistics/sugar-sweetene...

SSB consumption has quite robust evidence (including many RCTs) showing that they are particularly bad for metabolic health and consumption continues to increase globally (and has not decreased, but actually mildly increased in the US as well): https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8778490/ (Fig 1 and Fig 2)

I don't track this space as closely now, but for anyone interested, a few interesting reads on some of the stuff I mentioned:

Some recent RCTs:

Hall, Kevin D., Alexis Ayuketah, Robert Brychta, Hongyi Cai, Thomas Cassimatis, Kong Y. Chen, Stephanie T. Chung, et al. “Ultra-Processed Diets Cause Excess Calorie Intake and Weight Gain: An Inpatient Randomized Controlled Trial of Ad Libitum Food Intake.” Cell Metabolism 0, no. 0 (May 16, 2019). https://doi.org/10.1016/j.cmet.2019.05.008.

Schwarz, Jean-Marc, Susan M Noworolski, Ayca Erkin-Cakmak, Natalie J Korn, Michael J Wen, Viva W Tai, Grace M Jones, et al. “Effects of Dietary Fructose Restriction on Liver Fat, De Novo Lipogenesis, and Insulin Kinetics in Children with Obesity.” Gastroenterology 153, no. 3 (September 2017): 743–52. https://doi.org/10.1053/j.gastro.2017.05.043.

Donga, Esther, Marieke van Dijk, J. Gert van Dijk, Nienke R. Biermasz, Gert-Jan Lammers, Klaas W. van Kralingen, Eleonara P. M. Corssmit, and Johannes A. Romijn. “A Single Night of Partial Sleep Deprivation Induces Insulin Resistance in Multiple Metabolic Pathways in Healthy Subjects.” The Journal of Clinical Endocrinology and Metabolism 95, no. 6 (June 2010): 2963–68. https://doi.org/10.1210/jc.2009-2430.

Some interesting mechanistics:

Izumida, Yoshihiko, Naoya Yahagi, Yoshinori Takeuchi, Makiko Nishi, Akito Shikama, Ayako Takarada, Yukari Masuda, et al. “Glycogen Shortage during Fasting Triggers Liver–Brain–Adipose Neurocircuitry to Facilitate Fat Utilization.” Nature Communications 4 (August 13, 2013). https://doi.org/10.1038/ncomms3316.

Moorsel, Dirk van, Jan Hansen, Bas Havekes, Frank A. J. L. Scheer, Johanna A. Jörgensen, Joris Hoeks, Vera B. Schrauwen-Hinderling, et al. “Demonstration of a Day-Night Rhythm in Human Skeletal Muscle Oxidative Capacity.” Molecular Metabolism 5, no. 8 (August 1, 2016): 635–45. https://doi.org/10.1016/j.molmet.2016.06.012.

Mouse model, but this team at UCR has been doing a series of studies over the years that's also very interesting:

Deol, Poonamjot, Jane R. Evans, Joseph Dhahbi, Karthikeyani Chellappa, Diana S. Han, Stephen Spindler, and Frances M. Sladek. “Soybean Oil Is More Obesogenic and Diabetogenic than Coconut Oil and Fructose in Mouse: Potential Role for the Liver.” PLOS ONE 10, no. 7 (July 22, 2015): e0132672. https://doi.org/10.1371/journal.pone.0132672.